the s2k is my first stick.... ive realized driving a stick correctly wil take time or at least for me... its been practically a year since i bought the car, but i didn't do much driving , but since im going to school i drive it everyday and sometimes the shifts aren't that great and it gets annoying and frustrating...

 

As I saw mentioned above... Rev Matching is important.

When between shifts, match the RPMS of the engine to the (driveshaft?)?

I don't have an S2000, so I don't know the gearing... But here's an example.

Say you're going 40mph in 3rd gear, and your RPMs are 3,000.
When you shift to 4th gear at 40mph, they will drop to 2,000.

So, between shifts, have the engine speed at 2,000 RPM so that when the next gear engages, the RPMs are close to normal. This should eliminate much of the jerkiness.

Good luck.