The first rule is understand the recruiter's motivations. He or she does NOT work for you and does NOT owe you a damned thing. He or she is working for his client/customer - the hiring company (or sometimes his own, if they hire contractors). You have no basis on which to make demands of the recruiter, so the best you can do is manage your expectations, deliver what they expect of you, communicate effectively, ask smart questions, adjust your resume as asked (if asked), tell your story well (for which you have to figure out your story and then tell it well). A recruiter is a human being like any other, with foibles and always busy and have to eat what they kill (often working more or less for the commissions). They also have annoying habits like not getting back to you when you expect them to, not being clear on a job description (who is, these days?), not keeping you updated on the status of your application, etc. Expect little and be pleasantly surprised when you get a recruiter who's on top of his or her stuff and works efficiently. Help him or her help you, simply put. Be cooperative.
When you reach out to a recruiter about a position, even if you are a perfect fit on paper (to yourself or to most anyone), the recruiter serves as a filter and clearinghouse for candidates. It's his or her job to filter through tens or often hundreds of resumes (many of them for under- or over-qualified candidates) and evaluate not just the hard skills (coding, copy-editing, etc), but also the communication skills, fit with company culture, the possession of very narrow and specific skills needed for the job (employers are extremely picky these days), schools, internships, previous employers, reasons for leaving or termination, etc. Cut the recruiter a break - the job is hard and often thankless - lots of asshole candidates.
Always be unfailingly polite and cooperative, as well as responsive and timely. Listen carefully, ask good and intelligent questions, be respectful of their time. A good recruiter on your side can easily make or break a prospect for an interview.
Remember - they know the client (often your next boss) much better than you do (although your research should tell you a lot - more on this later). They can give super valuable pointers on your prospective boss's psychology and character, specifics needs, likes and dislikes, things to emphasize and to keep quiet about, plus other insider information.