More debugging
The debugger doesn't actually fix your code for you. It steps through code. How does it help? Adela shows us.
Debugging
Goat party planner
Fix the bugs in Cthulhu's party planner
Read code actively
When code doesn't work, the first thing to do is carefully read through the code.
Incremental testing
Write a little code, then test it. Write a little more code, then test it.