Fast and powerful down picking is essential if you want to become a mighty good riffer. Even for playing guitar solos, down picking is a very commonly used and useful technique. The best thing about down picking is that you get a nice uniform sound for every time you hit the strings with your pick unlike alternative picking. The dynamics of a down stroke and up stroke is so very different. So there are times when you would require only down strokes to get the desired sound. It is a skill that you should have in your arsenal.
Now how do you improve your down picking? There are two important things about down picking, speed and power. Specially if you want to use it for playing some powerful guitar riffs you must have both to make it sound good. Now here are some tips to improve your down picking
To improve power: You must remember that dynamics is very important and you want that skull crushing powerful sound when you are using down picking, specially when you play riffs. So always play powerfully when you practice. Its going to hurt a little at first. Your muscles will become slightly sore. If your wrist muscles tense up then take a break for few minutes and resume the practice. Play one part of a song that you like that uses down picking. You don't have to play the full song at the beginning. If you do that then within few months your wrist muscles will develop the power and you will be able to play the whole song. And slowly you will develop the power and control to play few songs using powerful downstrokes. Always remember, if you can play powerfully, you can also play with light delicate touch if its required. But if you don't practice this then your wrist muscles wont be able to deliver the sort of power that is required when you will need it.
To improve speed: The most important thing for improving speed is economizing the pick movement. You don't want to move your wrist too much, you don't want to move your pick too much cause that's just going to waste time and energy. You want the pick to stay very close to the strings and you want to play with minimum movement of the pick. To maintain good power while minimizing pick movement can be a challenge and that would require few months of good practice. You have to understand that its not going to happen in a day. It will require some time so you need to have the patience.
