Present or past tense

I think there is quite a big difference between using present and past tense. Past tense allows for more description, longer sentences and more reflection and can also add a layer of retrospection as the reader assumes the outcome is known and the narrator is talking from somewhere in the future. With present tense your narrator is in the moment and the voice will change - you will use more direct language, shorter sentences, and it will feel less thoughtful and more colloquial - more like speaking than writing. Present tense makes for immediacy and suspense, but it is also more demanding of the reader's attention and a whole novel written in first person present tense could be quite tiring to read. I think it depends on what kind of story you're telling, what kind of narrator you have, whether you want to be able to foreshadow events in the "future" which you could do in past tense but not so easily in present (you could but it would feel more like a literary device). I'd suggest reading some books written in both and see what the difference is and decide which treatment your story and character need.

Personally, I detest present tense. I picked up the Hunger Games to find out what the fuss was about and couldn't get into it at all. It's just my opinion however.