I earn more than 1 million points a year, and 6 of my favorite strategies for racking up rewards don't even require a credit card

Associated Press

If you're booking a stay at a Hilton property like the Grand Waikikian at Hilton Hawaiian Village, see if you're eligible for a bonus points promotion. (AP Photo/Caleb Jones)

• I earn more than one million points per year, in part thanks to cards like the Chase Freedom Unlimited and the Hilton Honors American Express Aspire Card.
• But if you already have all the rewards credit cards you can handle or if you prefer to steer credit cards in general, you still have options for earning points and miles.
• Earning a credit card sign-up bonus may be the quickest way to boost your stash of travel rewards, but you can also rack up miles by using airline shopping portals when you make purchases online.
• There are also dining rewards programs like American Airlines AAdvantage Dining that earn you bonus miles or points when you link your credit or debit card to your loyalty account.
• Read more personal finance coverage.

Rewards credit cards are a great way to reduce your travel costs or splurge on vacations that would otherwise be out of reach. Thanks to using cards like the Chase Freedom Unlimited and the Hilton Honors Aspire Amex, I'm able to earn more than one million points and miles per year - and those rewards unlock a lot of travel.

But what do you do when you've spent the big welcome bonus and don't want to get another credit card, aside from flying with one airline or paying for hotel stays? If you're in this position, there are still plenty of ways to earn more rewards. Here are six ways to earn more points or miles that don't involve signing up for a credit card.

Shopping portals

Most people shop online these days and there's no easier way to earn extra miles than through an airline shopping portal. All the major frequent flyer programs have their own shopping portals, where you can earn as many as 36 miles per dollar spent.

Simply register for these portals using your frequent flyer account number and simply click through to your favorite merchants when you're ready to shop online.

• American Airlines AAdvantage eShopping
• Alaska Airlines Mileage Plan Shopping
• Delta SkyMiles Shopping
• JetBlue TrueBlue Shopping
• Southwest Airlines Rapid Rewards Shopping
• United MileagePlus Shopping

Around the holidays, some of these portals also offer tiered bonuses based on spending. It's worthwhile to check these portals for special bonus point promotions, so you're earring the most miles possible.

If you want to save time while searching the highest shopping portal payouts, simply head over to CashBack Monitor, type in the merchant's name and you will get a list of portals paying out the most points.

Dining rewards programs

Every once in a while, I'll go out to dinner, pay the check, then get an email notification that I earned extra airline miles through a dining rewards program. Whether you're paying with your Chase Sapphire Reserve, the American Express® Gold Card, another card that earns bonus rewards on dining, or even a debit card, you can earn lots of miles this way. Simply sign up with a dining rewards program of your choice and register the card you most often use to pay for meals (debit or credit).

These dining rewards programs will automatically issue miles when you swipe your card at participating restaurants. All of them offer various bonuses when you join and spend a certain amount within the first 30 days.

• American Airlines AAdvantage Dining
• Alaska Airlines Mileage Plan Dining
• Delta SkyMiles Dining
• Hilton Honors Dining Rewards
• JetBlue TrueBlue Dining
• Southwest Airlines Rapid Rewards Dining
• United MileagePlus Dining

It's important to note that while you can join all of these dining rewards programs, you can't register the same card with more than one. They're all part of the same network, so if you try to register the same card with multiple programs, your card will un-register from the previous program you linked it to.

Miles-earning debit cards

Credit cards aren't for everyone, but in an increasingly cash-free world, most people need some form of card payment: That's where debit cards come in. There are currently two banks issuing mile-earning debit cards:

Suntrust SkyMiles debit cards

Suntrust bank offers two mile-earning debit cards, the Delta SkyMiles World Debit Card and the Delta SkyMiles Business Debit Card. Both cards come with a 5,000-mile welcome bonus issued after your first purchase. Cardholders earn 1 mile per $2 spent, which is half what you'll earn from a Delta SkyMiles credit card.

These cards also have annual fees of $95 and $120 respectively, which also puts them at a disadvantage compared to Skymiles credit cards. However, for folks who don't qualify for credit cards or simply don't wan the responsibility, these Skymiles debit cards are a good alternative.

Bank of Hawaii

Bank of Hawaii has two mile-earning debit cards tied to the Hawaiian Miles program:

• Bankoh Hawaiian Airlines Visa Debit Card
• Bankoh Hawaiian Airlines Visa Check Card for Business

Both cards only earn 1 mile per $2 spent, and you need to pay $3 per month in lieu of an annual fee. There's an earning cap of 1,000 miles per month on the Bankoh Hawaiian Airlines Visa debit card. That may be a hindrance for some people, considering a free flight on Hawaiian Airlines starts at 7,500 miles one way.

Airline and hotel bonus point promotions

One of the easiest ways to earn more points without credit cards is to sign up for airline and hotel bonus point promotions. For example, Hilton Honors is currently running a double points promotion for hotel bookings made directly with Hilton. With just a few clicks of the mouse, you'll earn twice as many points as usual on your Hilton bookings.

How do you keep up with these bonus point promotions? Make sure you're opted in to receive marketing emails from your favorite airlines and hotel chains. You'll get notified when new offers appear and all you have to do is click through and provide your rewards number register.

Since marketing email can stack up, you may even want to create a separate email address linked to all your rewards accounts. That way, your point-earning activities won't interfere with your daily work and personal emails.

The United MileagePlus X app

The MileagePlus X app is one of the most underrated ways to earn extra miles. Simply download the app, log in with your United MileagePlus number, then check for participating merchants in your area. These include popular retailers like Starbucks, Nordstrom, Lowe's, Foot Locker, and more.

When you get to the checkout line, simply enter your total due into the MileagePlus X app. You will essentially buy a gift card in the exact amount due and earn up to 5 miles per dollar spent. Simply show the code to the cashier, they'll scan it, and you're done. If you end up returning the item, you'll receive your refund in the form of a store gift card.

What's really great about the MileagePlus X app is that it allows you to earn valuable United miles without having a credit card. In fact, you can link your debit card to pay for the gift card purchases or double-dip by using a United MileagePlus card like the United Explorer Card. Either way, this app lets you accelerate your miles-earning at some of your favorite merchants.

Earn points through partners

Whether you're in the market for a new cell phone plan, hotel, Airbnb, dog sitter or looking to refinance your student loans, you can earn thousands of extra miles thanks to airline partnerships with these vendors. It's worthwhile the check the partner offers page of your frequent flyer programs to find out all the ways you can earn more miles without credit cards.

We've highlighted a few below:

American AAdvantage

• Earn up to 25,000 miles when activating a new Sprint account.
• Earn 4,000 bonus miles on select RocketMiles hotel bookings.

Alaska Airlines Mileage Plan

• Earn 100 miles for every $300 spent at participating Carrs-Safeway locations in Alaska.
• First-time Rover customers get a $30 credit and 3 miles per dollar spent on rover.com

Delta Air SkyMiles

• Earn 1 mile per dollar spent on Lyft rides.
• Illinois Energy customers earn a 2,500 bonus plus additional miles every month.

Southwest Airlines Rapid Rewards

• Earn up to 50,000 Rapid Rewards points for refinancing your student loans through SoFi.
• Earn 1 point for every gallon of gaspurchased at Marathon gas stations.

United MileagePlus

• Earn up to 80,000 miles when financing a loan through LendingClub.
• Get 25,000 miles for a home mortgage through Quicken Loans.
• Earn up to 13,000 miles and 20% off Lifelock with Norton membership.

• More credit card coverage
• What's the best airline credit card?
• The best cash-back credit cards
• Southwest credit card review
• Best rewards credit cards

Disclosure: This post is brought to you by the Personal Finance Insider team. We occasionally highlight financial products and services that can help you make smarter decisions with your money. We do not give investment advice or encourage you to adopt a certain investment strategy. If you take action based on one of our recommendations, we get a small share of the revenue from our commerce partners. This does not influence whether we feature a financial product or service. We operate independently from our advertising sales team.

Business Insider may receive a commission from The Points Guy Affiliate Network, but our reporting and recommendations are always independent and objective.

Please note: While the offers mentioned above are accurate at the time of publication, they're subject to change at any time and may have changed, or may no longer be available.