Don't play junk hands ever (except to steal, which you'll be doing vs nits with almost everything from the button). Speculative hands are ok to play in the early stages, and I am a firm believer in playing a loose double up or bust strategy early (if I'm going out might as well go out after a half hour rather than 3), but in general you want to keep the cost of playing laggy at minimum. Try not to play OOP as much as possible, limp into some pots and minraise into others (your limping range is speculative hands that can take down multiway pots when they hit, though you wanna raise some of those as well). C-bet pots you can take down safely (never for more than 2/3 pot), but for Christ's sake, don't be 2 or 3-barreling almost any spot or chasing down expensive draws, it drains your stack. And that is your tournament life.
As for the cash game comparison: Yeah it's kinda like a cash game in early stages, but your edge is smaller. You can't reload so you only have your starting stack and that's it, and the effective stacks are always smaller than cash because most people are gonna be hovering around 50-60bb after a few rotations.