Hi there. Welcome to CAP.
Put up the casinos that you play at regularly yourself, know a lot about and feel comfortable give you a good service to start with. It’s important to show players you know what you are talking about.
Then as you learn about who does what and how, add more gradually. Try to spread your options around, but there’s no rush – you can start with a few and build over time. there’s no limit as long as your website grows with good information accordingly. With descriptions, I would suggest probably a maximum of 5-10 as a maximum on one page unless you are doing charts.
Good luck
Simmo!