Start with Travel Account Call Center Explained (13 min, Kwestyon), then How to Get Clients as a Travel Agent With No Experience (16 min, Travel Agent Haven). All 11 lessons here are free, from the teachers' own official uploads. You'll need laptop stand, noise-cancelling headphones, second monitor and a few more basics (about $270 of kit). The book to keep beside you: The Business of Tourism by J. Christopher Holloway.
What you'll need
Laptop stand: Screen at eye level for long study sessions.
Noise-cancelling headphones: Focus through long video lessons.
Second monitor: Video on one screen, practice on the other.
Wireless keyboard and mouse: Comfortable for hours of typing.