This is the hardest part. You can spend a fortune or get by on just a little. You can purchase a complete curriculum from a publisher or mix and match. You can buy your books new or used . Set up a record keeping system.
Most support groups provide the record keeping forms that they require.
Your record keeping can be as simple as a daily journal or as complicated as setting up daily and weekly goals. I check them off as they are completed. Quarterly, I make a summary of what was completed and covered in each subject. Check out the homeschooling magazines available online or by subscription. It's a great way to reward your students for a job well done.