A good jacket should be next on your list. One important aspect of your jacket is that it should not only be waterproof but breathable too. If your jacket is only waterproof it will not allow any moisture to escape from the inside. As condensation builds your clothes will become damp and the jacket will start to cling. There is a wide range of breathable waterproof fabrics on the market such as Gore-Tex, just check the label. During the drier summer months a windproof jacket may be preferred as these are lighter and more breathable than a waterproof jacket.
Another thing to consider is the length. A jacket finishing above the waist might make movement easier but it won’t cover your pockets and might allow water into your trousers. Too long and you’ll restrict your movement. A hood is an important feature. Ideally you'll want one that can be tightened and adjusted to keep out the wind and rain. If the hood can be removed as well that’s another plus. The number of pockets and their position is also worth considering. A large, easy to reach pocket is ideal for storing a map. Adjustable cuffs will make sure your arms are kept dry.