I knew several CAD packages before advancing on AutoCAD, starting with Version 2.5. The R9 edition was my first purchase. After 1986 when I launched my present consulting company, ACAD projects became my bread & butter. With Sausalito only an hour away, we had a pretty good support group to lean on.
The fastest way to ramp up after learning the basics is to pick two commands a week and master them. Repeat each week, after week.
If you are just fiddling about and wanting to make a simple project Ã¢â‚¬â€œ forget about ACAD and just use AutoCAD-Lite which I believe could be a free download and it is vastly easier to use. ThatÃ¢â‚¬â„¢s if yer committed to Autodesk products. However I think there are better tools out there. Personally, I know ACAD like the back of my hand and thatÃ¢â‚¬â„¢s what I use for all accurate drawings and models.
Shortcut to modeling your bike:
Take a picture of it from far away to reduce the lensing distortions but in high-enough resolution that you still get a good shot. Naturally the frame should be perpendicular as much as possible to the viewing plane. Also place a tape measure in the shot for linear reference. Or have the frame against cardboard with a grid drawn on it with known measurements so you can scale it correctly when you bring the image into ACAD or whatever.
Anyways, thatÃ¢â‚¬â„¢s how I got started.
Best of luck, KF