What are good tips/ways to improve my writing on chalkboards? Recently, I have started to regularly write on chalkboards. I have also found out that I am quite terrible at it, although my handwriting is quite good.

Any tips or strategies for a beginner are welcomed.
This is going to sound stupid, but I've seen it work. Try dividing the blackboard with vertical lines to create narrower "pages." This will make it easier to write in a straight line and will discourage you from writing too large. Of course, the "pages" need to be large enough that you don't write too small.