The list of essential tools for pruning is short, but careful selection is necessary,
The list of essential tools for pruning is short: secateurs, a Japanese handsaw, a pair of loppers, a hedge shear, a pole pruner and a stepladder. When I am pruning I have two indispensable tools, my secateurs and my hand saw right at my fingertips. The secateurs fit into a leather holster attached to a belt and the handsaw in its scabbard hangs from a clip from the same belt. This is not a belt for my trousers but a separate tool belt for work. You constantly need your hands free while pruning so having a convenient, safe place for your tools is essential.
There are many kinds of secateurs, and if you are going to take up pruning seriously I recommend Felco. They have a wide range of sizes and styles, right and left handed, and a model or two with a revolving handle that is designed to ease the friction of use. Whichever you choose, they are extremely durable, well built and have many replacement parts. Secateurs require very little maintenance. Keep the joint between the handles lubricated, and keep them sharp -- sharp tools, good clean cuts. There is much discussion and techniques about secateurs sharpening. I like to keep it simple and quick. I use a small 6-inch triangular file, and run it between the anvil and blade, resharpening the bevel on the edge of the blade.
The Japanese pruning saw is the second essential tool. As soon as branch size gets beyond the capacity and ability of your secateurs and your hand strength, the saw is the tool to use. I call it a Japanese pruning saw because the modern innovations on these saws were first employed in Japan. These saws cut on the pull stroke, towards your strength, the teeth all lean back towards the saw handle. The other important innovation was the creation of another cutting surface at the tip of the teeth. These saws are usually made from reasonably hard steel, meaning that they stay sharp a long time if kept out of the dirt, and they are difficult enough to sharpen, that when the blade is dull, I replace it. There are many styles and manufacturers to choose from; Silky is a premier Japanese brand.
Loppers are a handy tool, most especially for shrub and hedge work. They are an extra-large secateur held with both hands. Because of the long handles, there is a certain loss of control. I do not use loppers to prune trees. The cuts are never the quality or accuracy you get with a good sharp saw. The job that I use them the most for is thinning and cleaning out the bottom of shrubs. I sharpen them the same as I do my secateurs. There are many brands, styles and prices, The Felco loppers, a bit pricey, are the nicest I have ever worked with.
Hedge shears come in many styles, sizes and qualities. It just depends on how much you need to use them and your budget. I have seen on the Internet beautiful hand-forged Japanese shears, whose cost runs into the hundreds. Most people don’t need that. Do try to find ones with a good steel blade that will take an edge. I do not do a lot of formal shaping, so don’t use a shear much. They can be handy for cutting new ground shoots on shrubs.
A pole pruner is a essential tool for most of us. No matter how tall you are, there is always a branch out of reach. The pole pruner is a tool everyone thinks they need and so lots of low quality models are available at most hardware stores. These may be cheaply built, but they don’t give them away. They are not a good investment; bad design, poor workmanship and low grade materials are common in "homeowner grade" pole pruners. This is a time to step up a grade and buy a professional arborist tool, much better designed, with quality steel and very durable. You get a lot more tool for your buck. I have used Marvin pole pruner heads for years and highly recommend them. Typically, this tool will be cheaper than the “homeowner special" and a better tool in every way.
Ladders are another essential tool for tree work. Always handy for starting your climb, they also give you the reach often needed. One of the handiest and most used of my tools is a sturdy four-foot step ladder. I am on this constantly when pruning apple trees. It has just enough height for work in the tree, but not so much that it doesn’t fit under the tree. For general tree work you can get a lot done with an eight-foot. This ladder is mostly used on the outside edge of the tree. The beauty of the four-foot is that it fits under the crown of many trees. The cheap aluminium ladder is to be avoided. A good ladder does not quiver when you climb it. If you are going to spend much time on a ladder, buy a strong one.