The cardinal rule: Do not buy tickets, hotel rooms, or anything else before asking your boss for permission for the dates you planned.
Remember you are asking your boss for vacation time — not informing or demanding them.
"Pick a good time to ask such as when the office is relatively quiet or when you have just delivered a project," Hedblom said.
Don't ask in the midst of a deadline or after your boss just left a stressful meeting with his or her boss.
You could try:
"I would like to take off the second week of July. Does that work for you?"
Instead of:
"I'm going to San Francisco the second week of July. Just wanted to let you know. Thanks!"