To the Original Poster: There is a book on clicker training. You should see if the library has it, I know mine does. If the library doesn't have it, you may be able to ask them to get it for you from another library.
I've never taught my horse kisses (at least on the face) as I feel it is dangerous. I've taught targeting, Spanish walk, and bowing. Spanish walk is something to be very careful with, as you can get kicked.
For the first lesson in clicker training, I teach backing up. I do not want to reward pushy behavior. By asking to back the horse is still respecting you (and learning to move away from you to get that reward, rather than towards you). My horses already know how to back, i just use it as an introduction to the clicker. Plus it is very useful to be able to use the voice command for back up and not have to have a lead on, not have to hold a whip up, or worry about the horse running out the gate when I am leading one in.
Of course when starting, always use a halter and lead. And never ever give the horse a treat for putting his ears back!
Targeting an object (like an orange cone) is one of the easiest things to teach and should be one of the first few lessons. Picking up an object should be next on the list.
If your horse is pushy, you need to do some groundwork in the roundpen. Even if I did teach my horses "kisses" on the face, I don't think they would ever "dream" about nipping me. My old mare social grooms with me without using her teeth, my young mare will kiss me all over with her tongue and doesn't use her teeth either. My young mare is a very kissy horse. I didn't teach her to do it, but she loves licking your hands/arms or even your jacket. I think it is an affection thing with her.
Neither of them ever put their ears back towards me though. If they are dis-respectful, they get lunged, and they know it!
Now if your horse is more dominant, pushy, or generally disrespectful, I probably wouldn't teach clicker training.
You may need to work on backing up without treats (as he will probably show some attitude). Introduce the treats once he can back up on his own, just by you shaking the lead. Never treat all the time! Reward him inconsistently or if he looks like he is really "trying" hard.
I use treats, just not very often and not every time I work the horse. I usually use treats if I am asking for a "special trick", or if I am loading the trailer. Every once in a while if I hit a snag while training, but not often.