Car starts sometimes, sometimes just clicks?

I have a 1996 Nissan Altima (Automatic). Every morning when i go to start it it starts just fine, or if i haven't driven it in awhile, it starts fine. However, sometimes...maybe 15% of time, when i have driven it recently and go to start it again, i just get 2 click sounds, wont start at all. Usually after wiggling my cable that connects to my battery around it would start. However i eventually got tired of doing this so i went and bought a new terminal, cleaned the battery post, cleaned it all up..and tightened it perfect. Now whenever it decides not to start, wiggling it doesnt do anything, after it charges for about an hour it starts, but i think it may be just because it cools down, not because the battery is actually dead (brand new battery..should be fine) pleasee hellpppppp, i dont know anything about cars.