No, it wouldn't hurt as long as you use good form. Pick a weight that will allow you to do 8-10 reps with good form.

It's been my experience that too many women spend a lot of time using the 3-5 and 8lb weights and are afraid to go heavier because they don't want to "bulk up". Although there are some women who can gain muscle easily, for most it takes a lot of effort and dedication to build "large" muscles. For most, lifting heavier results in more strength and some hypertrophy. The definition will come as you lose your body fat.

Meanwhile, muscle is very metabolically active tissue (unlike fat), so it takes a lot more calories to build and maintain muscle.

If you aren't confident with your form or how and what you should be working, a personal trainer is a great way to start. (and I'm not just saying that because I'm a personal trainer either. I've hired a trainer for myself before!)