Originally Posted by JARblue

Shifts that are jerky, are most likely to be driver error (a very small number will be from actual mechanical problems with the clutch or transmission). To eliminate jerkiness, all you have to do is ensure that your RPMs are appropriate for your speed and gear shift. It not exactly a simple procedure, but if you're not getting smooth shifts, the simple fact is that you are not rev-matching properly. Downshifting is a bit more tricky, but upshifting shouldn't be too difficult. When upshifting, you just need to be sure to release the clutch when RPMs are appropriate - it's going to take time, especially for a new MT driver, and will eventually just become feel. It's not rocket science, but it can be frustrating if you don't practice (and your DD route is generally not going to be the best practice method - find an empty stadium parking lot is my recommendation).

If you let out the clutch too quickly, the RPMs will be too high - solution is to wait a hair longer before letting out the clutch.

If you let out the clutch too slowly, the RPMs will have dropped too low - solution is to blip the accelerator to bring the RPMs back to the proper number.

If you have SRM, work on letting out the clutch steadily instead of dumping it - I find this virtually eliminates any jerking when downshifting. This isn't going to have any effect if you are downshifting from 5th to 2nd at 40 mph though... I'm talking about reasonable shifts for DDing.