How do I put baby down to sleep?

How does everyone put their baby down to sleep? My son (almost 7 weeks old) will fall asleep while being breastfed and sometimes while in his swing, the second I move to put him in his crib/play pen he wakes up and starts to cry. Up till now either my husband or I have been staying up while the other sleeps but we really need to change that. I have tried everything I can think of (swaddle, slowly putting him down, waiting different amounts of time before trying, etc) but he still won't sleep in anything else! Even when we put him down when he starts falling asleep he wakes up wide awake and we have a difficult time geting him to fall back to sleep again.