The following organizations can help you with the ins and outs of freelancing and/or starting your own business:
BOOK: The Young Entrepreneur’s Guide to Starting and Running a Business: Turn Your Ideas into Money!
VIDEO: 50 Groundbreaking Startup Ideas
ARTICLE: Inc.com: 60 Great Tools and Resources for Entrepreneurs and Startups
ARTICLE: Ryrob.com: 101 Best Side Business Ideas to Start While Working Full-Time (in 2018)