What's the correct way to leave cover?

When I'm in cover and I want to leave it (say when all enemies are dead and I need to move on) I often make a fool of myself - I usually end up rolling around or moving to another piece of cover while my squad-mates look on with withering distain (or that's how I see it). Often I find I'm 'stuck' in cover and I can only get out by jumping over the top of a barrier or rolling off the side when there's no more cover that way.

I'm assuming I'm missing something, what's the correct way to 'leave' cover and move around normally again?

Vaulting over the cover seems to be the most reliable way of leaving it, though that is not always what you want to do. The best way I found so far to leave cover without vaulting over it is to just walk backwards, usually this makes Shepard leave the cover. It doesn't always work, the cover system combined with the "One button to rule them all" choice of mapping nearly every action to one single button inevitably causes some situations where Shepard just doesn't do what you want him/her to do.

There is no "correct" way to leave cover. I personally prefer to pull away from cover (walk backwards) as that's what you had to do in ME1, but vaulting, rolling out, or simply hitting the A button (on 360, X on PS3, and I think space on PC) are all valid. Sometimes it's dependent on the situation as to which method will be the most effective.

My suggestion: learn and be comfortable with all the methods. Being able to effectively move from cover when you're not under fire will improve your skill at doing so while under fire.