Remember that all carb tuning happens AFTER the engine is fully warmed up
Starter jet sets the choke richness. Reduce this jet size if possible to allow the bike to run/warm-up on the choke for a minute before taking it off.
Idle adjuster screw is for setting the richness at dle (slide fully closed) and is a very fine adjustment. The engine idle speed should be set as low as possible to do this. Turning in should increase speed (leaner) and out is richer.
Idle jet size adjusts the fuel output for cracked slide to about 1/8. Too rich will bluber (4-stroke) at slightly a cracked to 1/8 throttle while riding.
The slide cut-away affects 1/8 to 1/4. Most of the time you can get around changing this because of the wide overlap between the idle jet size and needle position.
Needle clip position adjusts 1/4 to 3/4. Mid ranges. Lowering the clip on the needle - raises the needle position and richens the mix. The needle taper and neelde jet can also be changed, but most people don't bother. This gets into some fine tuning for a specific purpose, like track racing for certain turns and stuff. Most Pedders just ride WOT when possible.
Main Jet size affects mixture from about 3/4 to WOT.
This is very basic list and they all overlap, but for the common guy trying tune his bike, this is a good starting point.