I stand stallions, but mostly QH's and such.
A few things to know is first of all, this makes you a commercial entity. Any personal liability policies you have on your stallion will automatically be cancelled (even if you don't charge money! Just the act of breeding, even for personal use, makes your stallion commercial).
Next, a huge thing you need to take into account is a contract. Having a complete contract is very very important. Address EVERY contingency you can think of. A four or five page contract is not unreasonable.
Next, by standing a stallion you are offering a professional service. You aren't doing the mare owners favors, you are obligated to offer the best service you can to maximize their mare's safety, fertility, and minimizes their expenses. Therefore, you need a PLAN.
1) How are you going to figure out when the mare is ready? Tease? Palpate? Have them arrive ready? Breed on the owner's demand? Cooled-shipped?
2) How are you going to breed? Live cover? AI? Hand-breeding? pasture?
3) How are you going to ensure the health of the heard? what's your breeding protocol? wash protocol? safety? disease?
4) How are you going to preg check? No guarentee? palpation? tease? blood?
4b) How will you guarentee this?
BIG thing to remember is the mare owner expects results... no infection, no injury, pregnant mare, QUICKLY. Everything you do needs to be well documented and well thought out. If the mare owner has issues, they will pick you apart!
I say this last bit just as a warning... a lot of people don't worry about tails, or about washing genital areas. This I think is very important, as would a mare owner. If you don't wrap tails, handbreed, and wash both the mare and the stallion's personal areas, they may (I definately would) take exception if there was any infection or injury, and may definately blame you for not getting the mare in foal. Yes, 95% of mare owners will be fine. But that 5%, even if its just one owner with a big mouth, can ruin your reputation and your stallion. So do everything you can to make things as smooth as possible
As far as the advertising, I'll leave that to the folk who know
As far as charge... the stud fee is the SMALLEST of the fees the mare owner will see! A good rule of thumb is to spend one to two times the stud fee on mare care, pregnancy, and foaling. Its expensive! With QH's, that may be $1000 stud fee, $3000 mare care!
Most minis and unproven horses are a lot cheaper than $1000, but if you horse is in high demand you can command a better rate. For my horse I think I'd start him around $250-400. Even that may be high, because I don't really care if nobody breeds to him. He's not standing at stud, after all. But he's a "grade" horse, unproven, and just a pet. He throws AWESOME foals, but I won't ever see one on my farm unless I really, really want one to carry on his legacy later in his life. Still, $250-400 would be a good place to start and see where things go. Other people who actually commercially stand mini studs can give you a better idea, I've not looked into their prices at all.