what should i be looking for and doing when i want to do a good tune up and service of my car? im asking all techies. please help me out.

 

dont have one man...i know people here know the specifics to look for when doing a tune up and stuff. like ---- that should be changed and ---- not to be changed. stuff that makes a difference and what doesnt. i read a post b4 but i cant find it now. if anyone can help me that would be great. thanks in advance