Let the recruiter or employer contact you first. That doesn't mean you shouldn't apply directly to company job sites, post to job boards like monster.com, or attend job fairs. You apply for every job that could possibly fit. You post your resume anywhere you can. What it means is that you don't call companies directly. You let them notice you.
Now, of course, if you have a friend that works at Company A and you are just dying to work at Company A, then you can pass her your resume and let her put it in front of the right people. You don't contact those right people yourself. You wait until they decide you're worth pursuing and answer their phone call when they want to talk to you. Same with recruiters or any other future employers. They must be interested in you.
In the interview, follow their lead. Don't volunteer things. Respond to their questions with only the information needed to answer their question. Listen carefully to the kind of things they're asking you and telling you about the job and the company. You may have to do The Rules thing and walk away (gracefully, at the end of the interview) if you sense it's not going to work out in the long run. That's OK.
Look casually around the office or conference room; don't focus so much on the interviewer(s) that you make them uncomfortable. They'll sense your desperation. Go with the flow; don't ever discuss your problems at your current or past jobs. The message you want to convey is,"I have no problems. I cause no problems. I solve your problems." This should be your mantra.
If there are silences in the conversation, wait for them to speak first or ask questions. Be reserved, professional, and serene. Let them do the work of coming up with interesting things to say; put them in the position of having to sell you on the position and the company. Your paycheck will thank you for it!