I want to get better at Esperanto syntax. What resourses are available for that?

What are you looking for? Explanations, exercises?

This is an excellent book that is more than worth the price if you purchase it; however, the contents are also available for free online Being Colloquial in Esperanto

PMEG, also available both in paper and for free online, is the best resource for looking things up.

Have a question about whether you are using something correctly, or how to say something? It's usually not too hard to find in PMEG, and there are good examples to illustrate the right and wrong ways to do things.