What size tires do I put on my F-150 with a 3 lift?

2006 Ford F150 Lariat 2WD, 5.4 L V8 Triton

I'm a girl getting a lift for pure appearance. I do not care about off road performance, I just want my truck to look good in the cheapest way possible.

At least you're admitting you're a poseur, that's more than most people are willing to do. With a 3 inch lift, you can probably fit 35's without too much issue. The increase in tire size will have an adverse effect on your effective axle ratio, and to get it back to stock, you're going to want gear with 4.10's, that will cost around $300-$400 for the parts and labor, but it's optional so long as you don't mind getting beat by a school bus in a drag race.