Education occurs most often in "real life" by becoming involved and learning the details as time progresses. Although there are several books on the topic, some so-called "how-to" or "silver bullet" books instruct readers to manipulate holes in the Google algorithm, which can quickly become out of date, or suggest strategies no longer endorsed or permitted by advertisers.
Of course you want affiliates with high commissions, but they should also have a solid reputation with high conversions and low reversal rates (you get $0 if people cancel after signing up). If they’re part of an affiliate marketplace like ShareASale or ClickBank you can see some numbers there. Companies likes Amazon/SiteGround are safe bets, otherwise do your research (or track your affiliate links so you can monitor their performance). Avoid affiliates offering huge commissions since this probably means they’re struggling to acquire/retain customers naturally. This will hurt your numbers (specifically your conversions/reversal rates).
Most newbies in affiliate marketing make the mistake of registering with too many affiliate programs and try promoting everything they see. If this is the path you are treading, then it will overwhelm you and you won’t promote the products properly. Take time to understand the needs in the market and search for products that will go well with your site’s topic.
Amazon's commission rate is pennies from each dollar of merchandise that you sell. What many people don't know is that there are affiliate opportunities out there that pay commission rates that are much more favorable, from $20-$100 (and even more). Browse affiliate networks like Commission Junction, Share-a-Sale, Rakuten and Ejunkie for opportunities and their general commission rate.