My son has dysgraphia (neuro-motor disorder which affects coordination, precision, and often mimics some symptoms of dyslexia). He was ambidextrous as a toddler but in Kindergarten was asked to pick a hand to learn to write with. He chose his right. Through third grade, his handwriting was illegible, did not follow the lines on the page, and often used a few letters rather than entire words. Things that helped him:

Initiating a reading program built for dyslexics (our speech therapist used Wilson)
Speech Therapy - learning to sound words correctly helped immensely
Physical Therapy - this helped most of all. Squeezing Koosh balls, manipulating clay, etc.
Mechanical pencils with soft grippers - I don't know what the difference is between mechanical and regular pencils, but it makes a big one.

If your school has a physical therapist, you may have to do some aggressive advocating to get your kiddo screened. They refused to test my son since, despite the challenges, he was performing either on grade level or slightly below. I took him to a private child psychologist who specialized in this area to get the actual diagnosis. Once I had that report, the diagnostician still had to meet on a district level to get the report accepted by the school before they would initiate therapy.