Consider the horse. If they were reliable in the past, probably will not be bad. But if they are a complete knott head, I would suggest a bit of ground work. Sack them out, Throw a saddle on them and let the blow up in a alley way or round corral. Warm them up a bit. If you saddle them up and they hump up, walk them around, take him to the round corral/alley way and try to make him buck. Let him blow up, much better without you on them. When they are warmed up, and calm, step on, be sure to be cinched up. A loose front cinch and back cinch is worthless. First few times, keep them in a small enclosed area. Work on your handeling from there. As they progress, take them outside the corral. A freshly farmed field is awsome for stepping on a green horse or a colt also. Makes them tired. Just takes time, patience and miles.
Or, find somebody that rides alot during calving and see if they will put 30 days on them. But that will cost you 10-25 bucks a ride depending upon the person. But that consistant work will make a horse out of them.
I break 3-6 horses during calving and AI season every year. Sell the good ones, and keep the awsome ones. Start with something young and dumb and when you are done, they can do it all, you just sit up there and let them do the work.
When buying a saddle consider what you want you have alot of options on everything from the tree, skirting and most importantly how it fits your horse.