I have put together a list of multicolor crochet techniques that everyone should try! These are great techniques suitable for any level.
Complete Guide to Changing Colors in Tunisian Crochet (Advanced Tunisian Workshop Week 2) - Heart Hook Home
How to Crochet with Two (or More) Colors
7 Incredible Multi-Color Crochet Techniques to learn Color Changes in Crochet - Nicki's Homemade Crafts
Crochet Tip: How to change colors in rows - Whistle and Ivy
Learn Crochet Color Work: A Beginner's Guide
Fair Isle Crochet Overview and Beginner Patterns - Blue Star Crochet
How to easily change colors between rows in amigurumi - Yarnandy
Crochet Educational Articles Archives - Nicki's Homemade Crafts
Surface Crochet - Ideas and Resources
Top 10 intarsia crochet patterns ideas and inspiration
7 Incredible Multi-Color Crochet Techniques to learn Color Changes in Crochet - Nicki's Homemade Crafts
30+ Variegated Yarn Crochet Patterns - Colorful Crochet
17 Variegated Yarn Crochet Patterns (All Free!) - Daisy Cottage Designs
How to Crochet with Two (or More) Colors
7 Incredible Multi-Color Crochet Techniques to learn Color Changes in Crochet