here's my current tech skill regimen:
i try to practice in three different ways, i feel like each has it's own advantages and help me practice different stuff.
1) Vs Bowser: Like joe said, lvl 1 bowser, .5 damage ratio, 9 hadicap on cpu. usually i only do this on fd and practice stuff like nair/shine timing, shine/grabs, nair/waveshine away, etc
2) Vs Nothing: Use the name entry glitch and fixed camera mode (Not neccessary, but i prefer it). practice moving around the stage. i think joe told me a good way to practice this was to make up little routines and then try to get them down and make up a new one. sometimes i just practice one specific things (im working on backwards waveshining right now, mostly to not avail). helps me get my movement speed up.
3) Vs different lvl 1s: usually fox, marth, falcon, peach. this is for practicing stuff like waveshining, wall infinites, drillshine->grab on marth, etc. after practicing the other two ways, it's sometimes easy to forget what actual comboing is lie for a second. i usually finish up with a few rounds against different cpus trying out different combos and stuff.
my two cents