1. respect my time. Three people from TekSystems called me in one day. There was no "Is this a good time to talk? I know I am calling you during business hours and your resume says you're employed", or any explanation about the course of conversation they were trying to have - just a whole lot of questions, which seemed to be scripted. Then one dude told me to go online to take a technical evaluation. "Please do this tonight." How about I have plans tonight, and please fuck off?
2. Respect developers, generally. I have been told repeatedly times "I never would guess you were a technologist" based off of appearance and personal presentation. What exactly do you think of the class of people I belong to? I spent years figuring out how to present as normal, so it's kind of flattering, but not very far down at all I'm a weird dude, and I take the contempt personally.
3. Respect me, personally. The relationship is sour to start with, because I am a resource to be packaged and sold. The trick - and I'm not saying this is easy - is to actually empathize with me.
4. Be concise. This is about respecting my time, but it's also about putting in respectable effort. Tell me in five sentences or less why you think I might want to work at this place. "You're a python developer with experience in GIS. This is a position writing python for GIS systems. It's a quail hunting company and remuneration is in-kind: 6-10 quail per week, depending on experience. Are you looking for work?" If you can't do that, you don't understand what you're trying to sell me, and you are an obstacle to get past rather than a facilitator.
5. Don't try to impress me unless it's with financial remuneration. "We have 20% growth and $50 million in gross income last year!" is worthless to me when asking for $55/hr ends the conversation. I don't care about your income if you're not sharing.
6. If I ask, be up front with me about how much money you stand to make off of me. It's hilarious how uncomfortable recruiters get when I ask what their take is. The only value to hiding it from me is to maintain a power imbalance, and I assume you're negotiating against me rather than for me.