Just because a stallion is on your yard is not really a great reason to breed it to your mare!!! If you are determined to breed from your mare you need to choose carefully the stallion it is an investment after all!!
Does the stallions conformation compliment your mares, what are her faults and weakness's?, what are his offspring like?, what are you aiming to produce?
Do you realise just how much work goes into breeding a horse not to mention the risk you put your mare in? And the cost too around £2500 to get a foal, if everything goes to plan, to weaning.
Can you keep an eye on your mare 4 weeks before foaling every hour, and when nearer every half an hour day AND night, some mares can go over by a month or more so you could end up with very little sleep for months!!!!
Have you thought ahead - do you have other mares and foals for her to run with, what about weaning? Do you have the facilities to keep younstock?
Have you thought long term, what if you had to sell at some point is the resulting foal going to be a valuable horse or just another ordinary animal to add to the tons already out there?
What is your mares breeding like? If she is of unknown origin you could get something totally different and nothing like either parent!!!
Good books to read about breeding are From Foal to Full Grown by Janet Lorch, and Foaling Simplified by Sue Caldwell - great pics!
Breeding is great fun and very rewarding, but hugely costly, risky and very time consuming and heartbreaking if something goes wrong - do you have the time/money to bottle feed a foal if need be?
Have you got a pic of your mare? and one of the stallion - what is he called and what breed is he? Does he have all the swabs and blood tests needed at the begining of every breeding season?