Depends what type of neighbours you want. The fields opposite the Other Stage are good, but for complete peace, camp just inside the Wicket gate. Most of the fields are a bit rough and the noise DOES NOT STOP so if you intend on sleeping, factor that in. Don't camp on a trackway and make friends with your neighbours- most importantly- flat ground. rolling around inside your tent on a hill is no fun. Without knowing any more about you, that's my general advice. Oh and don't campy under the electricity pylons- the hum will drive you nuts.
Tips? Forget all that. Just make sure you can always find your friends, it'll be overwhelming at first and you WILL get lost. But that's OK. Don't miss the sunrise, don't worry about getting from stage to stage for any band, and let yourself go.
Invest in a good torch, a good backpack, steer clear of the maniacs.
Arriving by coach is a bit of a pain, and depending on when you arrive be prepared to wait- have water with you.