I'm not totally happy with my handwriting and want to improve it, so the way I've done this is to write as often as possible in a dedicated Rhodia notebook. I write about anything and everything. I am trying out a way to write with upright letters that are joined up as you can see here:
And also cursive, with a right slant, as below. I even write song lyrics when a song comes up on iTunes which helps me learn to write neatly and quickly too.
Hopefully, in time, my handwriting will be super neat when written quickly. At the moment, it can be extremely messy when writing quickly (especially during busy on-calls!).