Watch Scam School, 52Kards, and PigCake
Stay away from most other stuff on YouTube.
Buy some beginner card books:
Mark Wilson's Complete Course in Magic (paperback has an extra chapter)
Joshua Jay's Complete Course
and Magic for Dummies .
Get some card specific books:
Royal Road to Card Magic
Expert at the Card Table
Expert Card Technique
Get anything from Michael Ammar and Daryl.
Find a magician near you (IBM, SAM, AMA, Magic Circle...) and start working with them. Don't develop bad habits because you're learning in a vacuum.
Don't get sucked into buying gimmicks or the latest trick... For $50 you can have a small library with everything you would even need to take you from hobbyist to professional.
Post here often for advice, ideas, feedback, and support...
Check out our sidebar for other helpful links.
I started after 30.