When I was in elementary & middle school my English was great but my hand writing was horrible! My mom suggested that I contact a friend of mine a state away and become pen pals. She said that I would have to learn to write neatly if they were going to understand it what I was writing. So my pen pal & I wrote each other letters twice a week for years! By the time I was in high school my hand writing had improved greatly! It still isn't perfect, but at least now people can read it :D
Just practice 10-30 min a day! Some people are just that way and can never change but it doesn't Hirt to try. There is also things you can get offline that you trace, that may improve it a little or even alot.
Well I remember having to practice penmanship in a public elementary school in the late seventies 20 min daily with a different letter. I hated it but my writing is very good and so is my siblings and friends. So.... practice daily and you should see an improvement. However who writes anymore with the advent of keyboard?
Slow down. Actually "try" to write more legibly. Most write poorly because they don't care how their writing looks. Then it becomes habit to write poorly. It's an easy fix though, you just have to try to write better.
Practice really helps. Get one of those cursive practice books at the drug store or teacher store and trace over the letters. Slow down and actually watch yourself. If you can, type. If you are doing a report, write it the best you can to get the ideas down, then rewrite before you turn it in. Putting a 3x5 card under the line helps me but you'll have to add the bottom of letters if you do that. Make your capitals tall. I used to do a demonstrate these techniques in a freshmen earth science class and it made their reports clearer so their teacher could read them.