Youness, the easiest legitimate way to make money online is to sell your non-used books, gifts and other things via eBay, Amazon Marketplace etc. However this can get tedious after awhile.
To spice things up I used the site listia.com to auction my unwanted things for points which I then won jewelry auctions on the site with. I concentrated on gold items on the site and then sold my gold to a gold merchant at are local mall and made like $500. It was a lot of work to get to that. However I didn’t mind because I learned all sorts of things about a new fields for me, jewelry, precious metals and stones.
The other answers are to start a blog and/or niche website. Like for me my subject is free advice and freeware data recovery software. When users come to my pages and look for free software to get back their data and they try the links I give and they don’t work, they click on my ads and I make money :-).
A word of warning however. I’m passionate about my subject and helping people, but I only make $400 a month. I have been at this now for 9 years! I have some computer training and programming skills and am making my own data recovery software now too. I have spent many, many hours at this and my income is slowly
creeping up. You usually can’t make money quick especially if like me you do this on your own and not as a member of a group.
It’s much easier to concentrate on a regular day job if you can find it rather than try to lift a heavier than air business off the ground. You need an independent subsidy or day job to your income for many years I think to make it work. This is probably true of most businesses, they start of small and as money losing ventures. 90% fail anyway.
However again if you are committed like I am, and have a subsidiary income or a regular day job that gives you some free time, than go for it. Find a niche subject that you are passionate about and are an expert and make a website, put Google adsense and affiliate ads on it, program programs and make a blog. To have an ever increasing amount of income, you really have to do it out of the love of the subject and helping people rather than making money per se.
Note I have extensive website where I list ways to make money like the ideas about taking surveys or serving on mock juries. It shows you how lazy I am or distasteful or inefficient these methods are in that I don’t follow my own advice and really don’t make that much money online yet, 9 years later…