Making money online can be done by writing reviews and by completing surveys, these don't offer amazing incentives but over time the money will build up, with some of the sites you could earn perhaps up to £20-30 a year, but we'd say you would be lucky to earn £15.
What happens? Well for the surveys, you sign up and periodically you will get sent surveys by email. You will not fit the demographic they want for some surveys and you will find yourself getting kicked off the survey quite quickly if thats the case, most sites will offer you a tiny reward for a "failed" survey usually a matter of pence, a completed survey can earn anything from 0p to £2 or 3, some of the sites say they have up to £5, but I personally haven't been sent anything above about £4 yet.
What do we recommend? Well for a number of years we have been using these sites...