I’ve read a lot of horror stories where Amazon has randomly closed people’s accounts for different reasons. Fair enough – many of these are due to breaches of their terms and conditions (e.g. failing to properly disclose links, not using the appropriate images and links provided in the affiliate dashboard, buying from one’s own affiliate links, etc.) but yes, if you fail to comply by their rules, you’re at risk of being shut down (and losing all the commission you’ve racked up). SO, don’t be a dummy, read the terms and conditions thoroughly and make sure you’re not breaching them.
Too much too soon. Stick to one website to begin with. Don’t get distracted by shiny new niches. This will only dilute your efforts. It’s absolutely not a waste of time to spend hours on end researching the very best niche for you to enter into. The commission, cookies, product and even the advertiser’s website all have to be excellent. The last thing you want to do is invest money in creating your own site only to send visitors to an advertiser’s site that barely converts a single sale. Would you buy from the advertiser’s site? Question everything before you spend a single penny on building your new site.