A simple formula:

1. Wear your pants 2-3 inches below your bellybutton. NO higher than that (unless you're at a Steve Urkel appreciation party.) Also NO lower than that - you're not a gangsta, and no one wants to see your underwear. Waist-size wise, seeing your butt is good, seeing your ass-crack is not good.
2. With your shoes off, the pant legs should barely touch the floor. Leg length is very important - nothing looks goofier than pant legs that sit too high and your legs show above your sock. If you refuse to pay for the pants to be custom hemmed, err on the side of leg length being too long rather than too short.

Pants have belt-loops for a reason. Use them. And no, wearing a belt is not an excuse to hang electronic gizmos off of it (see accessories.) If the belt matches your shoes (black or brown) so much the better. Minimal buckle size - avoid large intricate or cowboy buckles - keep it simple. One last thing: since you're wearing a belt, you can put away those suspenders.

Keep 'em blue or maybe dark black. No tie-died, no cheesy ripping, no stressed look. Definitely not tight and fitted, otherwise it looks like you're wearing teenage girl jeans. The jeans are just background - they've got to be there, but your top will draw all the attention.