OK, the beginning of this post is going to involve ranting. So just be warned.
Seriously, if you're going to do this to a tree, why not just cut it down and get it over with?
All right, I just want to make the point that pruning is not simple and it is not intuitive. It takes some education to do it right. The way you prune a fruit tree is not the way you prune a Japanese lace leaf maple. The way you prune roses is different from the way you prune flowering shrubs. You don't prune everything at the same time of the year. You don't even use the same procedures for plants in the same species. For example, there are three types of clematis and there is a different way to prune each type.
In other words, pruning is not a job that you can give to the lowest bidder and expect a good result.
So how should you approach the business of pruning? If you don't want to do the work yourself, hire a professional. For tree work, you'll want a certified arborist. For everything else, shrubs, roses, ground covers, perennials, etc., look for landscape gardeners and ask about their training. Have they taken a pruning class? (Don't expect the guys who mow your lawn to know what to do. They usually don't.) Ask for referrals at your local nursery. Community colleges with horticulture programs may also be a good source of referrals.
If you want to do your own pruning, I encourage you to do that, provided that you do a little reading first. One of the best books I've come across is the American Horticultural Society's Pruning and Training. It is well illustrated, easy to understand and well organized. It will take you step-by-step through the process of pruning hundreds of types of plants. You don't have to read the entire book, just go to the section that covers the types of plants you are interested in.
I also recommend Cass Turnbull's Guide to Pruning: What, When, and Where. Cass is a Northwest author, landscape gardener and the founder of Plant Amnesty. She has made it her mission in life to educate people about proper pruning and she does it with wit and wisdom. Whatever book you use, pay attention to the information on how and where to make proper pruning cuts.
Once you have acquired a bit of knowledge, you will want some proper tools. You don't need many. In fact, I would say that 90% of the pruning I have done in my life (which is quite a lot) has been done using only two things: a pair of pruners and a folding saw. It is worth the money to buy good tools. Cheap ones wear out quickly and break easily. By the time you're on your second pair of bargain pruners, you could have had a good pair all along. The brand I recommend is Felco.
I have used the same pair of Felco pruners for almost 20 years. Every so often I have them sharpened, and I think I lubricated them once with a shot of silicone spray, and that's about it. Felco makes several different styles of pruners which is a big advantage if you do much pruning.
For example, I have small hands. Regular sized pruners don't fit well in my hand and I quickly develop cramps. So I have a pair of F-6 pruners which feel like they were made for me. I can, and have, spent all day pruning using them without any problem. A friend of mine has problems with her wrist, something like carpal tunnel syndrome, so she bought a pair of F-7 pruners with a rotating handle. She says she had pretty much given up pruning until she found these. Now she can work comfortably. Felco also makes a left handed pruner with a rotating handle and several other styles to suit special needs. Having good tools can make all the difference in how much work you can do and how well you can do it.
Felco also makes great little folding saws. For big jobs, you will want a bow saw, but it isn't really practical in most situations because you can't fit the saw into tight places. The folding saw is small, light weight and amazingly sharp. Replacement blades are available.
Other tools you might need at some point include the bow saw mentioned earlier and a long handled pruner, also called a lopper. Loppers aren't precision tools and are best used to quickly chop away underbrush. For that reason, and because I rarely use them, I don't spend much on loppers.
Good pruning isn't really difficult, but there is a lot to know before taking sharp tools out into the garden. It is worth taking a little time to learn how to do it correctly. If you don't want to do it yourself, that's fine. Just don't turn the job over to someone just because he was the lowest bidder. You can't put the branches back on a tree once they've been cut off.