I use VNAV most of the time. To the above poster, contrary to you I find the TAI makes a huge difference. I tested it once, I started descent without it, entered the TAI information and there was a 1500ft difference. Although it's not the easiest thing to predict and normally I can't be bothered to work it out and just rely on the x3 tables when I get closer. I typically switch to V/S when on vectors to perfect a CDA. Level change I use when I'm high and need to get down whilst on vectors. If I'm high but still far out (e.g after a shortcut) VNAV with speed intervent does a good job. Really all depends on the situation you are in.
As mentioned above, it's a good idea to use the 3 times tables for your altitude, work out the miles you need vs the miles you have, take into account the wind and need to decelerate eventually. Basic airmanship.