If your handwriting has become tiny and virtually illegible (as is common with Parkinsonism and Parkinson's Disease), there are a few things I've discovered that might help you, too.
To return your illegible handwriting to readable, try the following:
1. Get some Manuscript Tablets from the 99 cent store or other source. Alternatively, get some wide-ruled notebook paper. Use the lines, which are about a quarter of an inch (one centimeter) apart, as guidelines for the size of your lower-case letters. Each letter must reach from one line to another. Yes, a quarter of an inch tall. Caps, and letters with ascenders and descenders, are two lines big.
2. Slow down. You'll notice that you can't scribble very fast when the letters are that large. I also noticed that with my micrographia I was trying to write in a hurry. By slowing down a lot, I could write legibly (when my meds were working). Slowly formed large letters can result. Writing slowly, for me, has proven more effective than practicing loops and swirls.
3. If you have Parkinson's Disease or Parkinsonism, try taking your medicine half an hour before meals or two hours after meals. It is said that food protein interferes with the carbidopa-levodopa.
I like writing on newsprint pads. (Newsprint is that brown, soft paper once common in elementary school. Its soft texture makes the pen glide across the page better. I also like PaperMate and Bic stick pens with the easy gliding ink. Some gel pens are good for ease of writing, too.
Writing annotations in the margins of books might look strange with large handwriting, but at least the notes can be read.