I think you've done the hard part. Getting someone to spank you is more difficult than getting him or her to do it right.
Communication is important. New spankers are often timid, scared of hurting their spankee, or just unfamiliar. Just explaining what you want from a spanking might be helpful.
I'm a spanker. An experienced spanker. I've given hundreds and hundreds of spankings and am very good at it. I can almost always get someone to where they want or need to be. But, I have lots of practice.
As some point, my wife and I decided that it would be beneficial for her to spank me. Very, very rarely, but on occasion. And, the first few attempts were miserable. Baby spankings which were really not worth the effort and frustrated both of us. It took a few spankings and more conversations to get her there. We discussed, with paint charts from the hardware store, what a properly spanked bottom ought to look like before one even thinks about ending the spanking. Then we discussed how one could tell when the spanking got to the effective point and was hard enough... there ought to be deep breathing and legs kicking. Then, we discussed, once spankings got to the effective point, how much suffering one ought to do. It might be appropriate for someone getting a mild spanking to experience five minutes of genuine suffering (the point in the spanking when the butt is really, really sore and the spanking starts being truly effective) and end up light red while someone getting a hard spanking might experience fifteen minutes of genuine suffering and end up deep red. And we discussed how the spanker has to stick to the plan, since the lesson doesn't really start and the submission isn't really submission until the spankee is sore enough that he or she is ready for the spanking to end. And, it took some practice.
But the result is that when I am spanked, and it is rare, it's a real spanking. If I'm told about it before hand, say in the morning or the day before, there's some genuine anticipation. It hurts. And, it's effective.
Hope this helps. As I said, I do think it's a lot easier to get someone to spank you right than it is to get them to spank you. Hopefully through open dialogue you'll soon be having to spend your fair share of nights sleeping on your tummy because yoru bottom so sore!