Present or Past tense, 3rd or 1st person?

[demondblood33]

Hey everyone. I'm writing a little short story for english class. Upwards of 30 pages. I was wondering which style I should do?
Should I go 3rd Present, 3rd Past? 1st Present? 1st Past?
I'm at a loss here.. Any advice would be appreciated.

Thanks in advance. =D