Worth learning to properly join-up letters (even if you then partially ditch it at a later stage) as you end up thinking entire words as you write them instead of letters, and it gets a bit faster (my own handwriting is sort of a mixture of print and joined-up).
If you're serious, get thee a handwriting-practice book - and just do it over and over again (maybe lay tracing paper on top of the pages to save using them up) until your hand and arm gets the muscle-memory fix on it.
E.g. search for 'cursive' in the jungley store.
Also, a fountain pen or very fluid rollerball is a good idea as you don't need to press so hard, leading to hand-cramps, etc.