questions you should be asking yourself are
1) Does the client need to run this script
2) Does the server need to run this script
Server doesnt require anything graphical to be run on it, eg dialogues, special effects such as heli dust etc etc
Server should control vehicle respawn, and keep a tally on the scores
weapon selection systems, player respawn etc needs to be run on clients only
Never trust a client to store important data, have the client send it to the server
AI control is serverside
hope that gives you an idea.
Every script is different, some are client only, some are server only, some are player only, some are mixed
lines you should be using are
?(Local server):
?!(local server):
?(local player):
?!(local player):
you can have scripts run on both server and clients, and have certain lines not read by cliewnts or server using the above lines
also use the above lines to execute scripts on the machine you want them, or to exit from scripts for the machines thast you dont want them to run on etc etc etc