2000 LS1 won't start

For about two weeks now, my car will not start all of the time. I have replaced the battery, and have checked all possible grounds and the fuses. When I jump the battery, there is a charge going to the battery from the alternator, so that isn't it. Sometimes, too, when I try to start it, it will hesitate and then start. I don't know what else to do but I want to make sure that I troubleshoot everything before I have to take it to the dealer.

is this a no start or a no crank? when does this happen most offen? right after shutdown? after overnight? how old is the battery? cold weather where you live? any other info would be helpful.

check all the connections... loose connections were my problem