This is meant as a general guideline for those children with handwriting problems.
Check that the child’s feet are flat on the floor and the table is at a comfortable working height (the forearms should e supported on the table).
Also check that the non-dominating hand is anchoring the paper securely. It should move down he page as the wrist moves.Incorrect pencil grips may be resolved in a variety of ways: 
Commercially available grips may help correct grip.
Use fingers as prompt for spacing or have a visual prompt, i.e. lollypop stick which can be decorated.
Try putting several sheets of carbon interleaved with paper and encourage your child to only go through one copy. Get them to practice ‘hard’ and ‘soft’ strokes so they get some feed-back on the difference.