Best small children begin with big zigzag, arcade, garland and loop patterns. Then show them how lower case letters are formed from these movement. Group, for instance, i, j, l, r, t, u, w, y, then n, m, h, and so on.
Forming letters from the right starting point will help greatly when they begin to join handwriting,
Sorry if that's didactic or unclear. It important to start correctly or habits have to be undone - much harder!
Start with pencil. Berol do a range of good inexpensive handwriting fibre tip pens. They include pens shaped to the fingers for both right and left handers.
Apologies for 'going on' but I have been able to 'rescue' children with poor handwriting by helping them to form their letters correctly, makes it all much smoother.
Please DON'T try to get children to write smaller. Big is best at first as handwriting invariable gets smaller as they get older. If someone has trouble keeping on lines let them write over 3 lines at first to get the ascenders and descenders in the right proportion.