Roofing is not difficult to do well as long as you have the right tools and supplies, and take the time to get the basics right. The first and most important thing when roofing is to be sure you are safe when working on a ladder or a high roof.
Work with someone else when doing roofing. This makes the job go faster, and improves your level of safety by providing a second pair of eyes to see potential hazards. On a steep roof, you will need a harness and a safety rope that is securely fastened to the peak of the roof by being tied around the base of a chimney or attached to a cleat secured to the roof. Wear sturdy, nonslipping shoes and heavy gloves to prevent shingles from abrading your hands. Wear a hat and sunglasses to prevent overheating and sunburn.
You can remove old shingles using a shovel, but it's faster and easier with a purpose-made shingle remover. This tool looks like a shovel, but it has notches in the end of the blade to catch the heads of the roofing nails and pull them out more easily than a shovel. You will need a hammer to nail in new shingles, and a means of cutting shingles. This can be done with a utility knife or a pair of tinsnips. A tape measure will come in handy for proper positioning of your new shingles to make sure they look right.
Depending on the condition of your old shingles, you may be able to install new shingles on top of them. This saves you the trouble of removing them and the expense of disposing of them. If the old shingles are degraded and lifting off the roof, you will have to remove them. If the tar paper under the old shingles is damaged or worn, it should be replaced too. For a basic re-shingling job, a roll of tar paper and some packages of shingles is all you need. If the roof sheathing has rotted or been damaged, you will need plywood to replace it.
The safest way to access the edge of a roof is scaffolding built up to the edge of the roof providing a solid footing you can walk on. If you don't have scaffolding and don't want to rent it, you can do the job using a sturdy ladder, but you must be sure the ladder is well seated and firmly placed. Once you shingle beyond the first three or four feet of the roof, you won't be able to reach the rest from the ladder and will have to stand on the roof itself. If the roof is too steep to provide secure footing, you will need cleats installed on the roof for safe footing.