Auto Paint Help

Hi Eyerock,
I am a long time mopar owner and troll of the site. I recently gave my 75 duster a long awaited paint job and it was my first one ever..
Needless to say i screwed alot of it up (but hey its about learning and having fun right?)
I learned not to get an old can of paint from your grandpa and spray it on for fun, because the expensive stuff from the store may not be compatible and it will bubble everywhere and cause much frustration and sanding.
Also I learned not to write on your car with jiffy marker (is anyone on this site as dumb as I am?) because it bled through about 8 coats of primer and 8 more of paint after sanding.
Anyways I was actually looking for a kind of tutorial on painting but i won't bother you for that. What I would like to know is this:
The final result of my car was not near as smooth as i thought it was going to be. I didnt much sand between coats because I didnt want to keep taking the same spots down to primer and in the end have 1 coat on it. I don't have a wet sander because it seemed more trouble than its worth getting it all wet, having the paper wet, drying it etc.

So to sum up: Whats the secret to a super smooth finish, and also is wet sanding mandatory or will dry sanding suffice?

Thanks!
-grades