Can anyone tell me a bit about affiliate programs for my website?

Can anyone tell me a bit about affiliate programs? I've been searching for an affiliate company for my website, but I'm swarmed with options!

My website is a mix of travel and personal development, so I'm looking to a good affiliate program that maybe includes travel (as in for jobs abroad for backpackers not flights) as well as personal development things.

Am I able to choose one site that has a lot of different products and promote them on different posts?