How to make a flavorful and juicy chicken breast?

I am not much of a cook, but I am really trying! I bake well but have difficulty with meat, especially chicken. I marinated chicken breast in a teriyaki marinade I purchased from the store, for 3 hours then baked it in a Pyrex (I don't have a grill or a broiling pan) at 350 for 45 minutes. It was cooked all the way through, so I took it out. I wasn't too hungry yet, so I had some an hour later and it was sort of dry with very little flavor, despite the marinade. :( What am I doing wrong? For some reason, I can't seem to cook meat. I have even thought of becoming vegetarian because I don't seem to like the way I prepare it, so I tend to avoid eating it. Any tips?