If its strong single strokes that you want to achieve, then, you'll have to practice playing single strokes! You can isolate practice for each hand (practicing multiple strokes with fingers and wrist) to strengthen them individually, but they still need to learn to work well together in order to achieve evenness. In order to do that well, always start slow. Allow your body to learn the motion slowly...remember, we're not machines...our muscles need time to memorise movements.
A good excercise would be to play a bar of 8th notes followed by a bar of 16ths at 1/4 notes = 50bpm. Play them non-stop for at least 5 mins. Then take a short break (a min or two) and do another set (I would repeat about 4-5 sets). Take another break and play a bar of 16ths follow by a bar of 32nd notes (similarly...do about 4-5 sets of 5mins). If this second exercise is too fast for you now, lower the metronome setting to 35-40bpm. Always practice with 16th note subdivisions clicking (for now) in order to ensure max accuracy in your strokes + time.
Good luck!
