Retain some control. If you upload photos of yourself, or friends/family with consent, it's worth going for the 'rights managed' licence option – otherwise you'll have little to no control over how your images are used (eg, you could star in an ad for haemorrhoid cream). See Alamy's page on understanding stock image licensing for more on the different types of licences.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.