I try for 3-4 times a week. I'm limited to the equipment on hand at home, which is pretty meager. It consists of a few barbells that have all seen better days, an incomplete set of weight plates (two 1.25 lb plates are currently being used to keep the kitchen table level, and one of the 10 lb plates I believe is in the garage, keeping the washing machine from bumping against the wall when it shakes), and two free-weight bars. So all I can really do are curls, pushups, crunches, squats (though ironically, those are better with a curling bar, which I lack) and some free-weight tricep/quad/peck stuff that looks vaguely sexual when I do them.
I'm quite sure I do them correctly--a couple of friends with pretty good physiques said so, at least--but despite nearly 3 years of this (and getting close to 40 lb curls) I'm still one skinny mofucker I guess either my diet sucks or I have skinny genes.