My top advice is:
1) Always remove full sentences/phrases not an odd word here or there as that can sound strange and stilted
2)Keep cut sentences in a separate document in case you want them (usually you don't, but you won't worry about it if you have them in a safe place).
3) Focus on saying things like "I did X because Y. From X I learned Z" you'll fit in less X's but it's the reasoning that shows your ability to think deeply and learn from things.
4) Good paragraphing is more important than making what you want fit in the line limit.
5) Really focus on whatever inspired you to do the course / anything you have done that demonstrates your interest in the subject