In a throwaway culture, tool maintenance can be intimidating to beginners. But taking the time to learn a few basic steps is satisfying. It will help keep tools useful for a lifetime and give you more money to spend on plants.
In the Pacific Northwest where I live it is possible to garden year-round. My good intentions are often overcome by dreary, wet weather, though, and I gradually stop going out to the garden at all. The garden doesn't really suffer much for winter inattention, but neglect can be fatal for tools. Even if you're a more persistent winter gardener than I am, autumn is a good time to give tools a more thorough clean-up than most people have time for during the growing season. Properly maintained, good quality tools can last for decades, but if allowed to rust they can become unusable almost overnight.
Whether you garden on acres or on a balcony, you probably own at least a trowel and hand pruners. Most gardeners also use some sort of shovel, a hoe, and loppers or a pruning saw. These all have similar care requirements: avoiding rust, keeping edges sharp, and keeping moving parts and attachment points in good shape.
Start by cleaning the tool. If the handle is wooden, give it a quick sanding and a light coat of linseed oil. To clean the metal parts, scrape off soil with a wire brush; use steel wool and a little oil to remove small amounts of rust. If there is too much rust, you may be able to order a replacement blade. If not, it is time to buy a new tool.
In most cases, it is not hard to sharpen blades yourself. Hoes should be sharpened each time they are used. Fasten the hoe in a vice, and using a sturdy file, grind a 20-degree angle on the beveled side of the blade. Sharpening a new hoe is hard, slow work, but once it has been sharpened, a few strokes with a file should be enough to renew the edge. Shovels and spades can be sharpened the same way, although they don't need to be as sharp. Pruning saws can also be sharpened with a vice and file, but their small, opposing teeth require slower, more careful work. I leave pruning saws to the professionals, but there are tutorials on YouTube if you want to try it yourself.
Hand pruners, loppers, and shears benefit from sharpening after each use, but many people put it off until fall. These hand tools can be treated much like knives and sharpened with a whetstone, or you can use a small bastard file, especially if there are any nicks in the blade. I only use water with my ceramic whetstone, but many gardeners use a little oil on the blade with theirs. Moving away from yourself, file the bevel edge until it's sharp. Then give the other side one stroke to pick up filings. Filing only one side maintains the bevel.
Fall is a good time to disassemble hand tools and clean the hard-to-reach parts. Remove all fasteners to take the tool apart and clean each piece with steel wool and a little oil if there is rust. You can use a cloth if there isn't. If parts of the tool are worn beyond repair or rusted, you can buy replacement parts for better brands on the manufacturer's website. Felco and Fiskars both include videos on their webpages that demonstrate how to switch out replacement parts. If replacement parts are not available for your tool, it may be time to upgrade to a better brand. You may spend less money in the long run.
If your shovel or hoe has a broken handle, the hardest part of replacing it is removing the rivet that holds the handle in place. Removing the rivet requires a Dremel, grinder, or hacksaw, which may be beyond the tool arsenal of many small-scale gardeners. If you have the proper tools, replacement is fairly straightforward. Once all the wood is removed from the shovel, drill a hole in the new handle, and simply screw or rivet (riveting is better) the new handle in place.
When your tools are clean, sharp, and well-oiled, you can store them in any dry spot for the winter. A useful trick year-round is to store tools in sand that has had vegetable oil added to. The sand removes rust and the oil prevents new rust from forming. Use a five gallon bucket to store shovels, and a smaller container for pruners.