the most important thing (IMO) is making sure you are in SOME type of work out routine. so many people just go into gyms and hop around from machine to machine and get next to nothing out of it..
if you search google there are TONS of different work out routines you are looking for. what i do is use a work out until i dont notice improvements anymore, then change to another work out (usually after two months or so)... but again, that is just what I like doing.. you just have to find what works for you