3.5 is good!
Your GPA depends entirely on its context. My GPA is only a 3.6, but I'm also an engineering major and very involved on campus. So far I have one acceptance and 8 total interview invites.
A lot of the applications process depends upon your test scores, the quality of your application, and apply early!
So, you could bring the GPA up a little...but you're in a good spot. If you're a strong applicant in other areas, a 3.5 shouldn't hold you back. In my opinion, it's better to have a good GPA and pursue interests outside of academics than it is to have an excellent GPA with no involvement elsewhere.