As i have mentioned it many times before in my blog that you can earn a lot of money by blogging.If google page rank of your blog is good than advertiser will pay you a lot of money for it. Apart from that you can earn money advertising some website on your blog. If a advertiser provide you a banner or text banner to advertise then he will pay you at a relevant rate per month.Think that you are getting a salary like money per month. To keep advertiser advertising on your blog is necessary and it totally depends upon your blog page rank and the benefit the advertiser is getting from advertising.If you have very nice blog well written and well designed. i mean a best blog which can attract people to it a lot will get more offer. If you a blogger and want to earn money then payingpost is one of the best website where you can start earning money.
i say how you will have to do it. if you have blog then it's ok otherwise you will have to make a blog either on blogger.com as it is totally free or by paying some web hoster.it shall be easy if you create a blog on blogger. keep posting on it day per day as per you hobby with lot of information whatever your hobby be. then make an account on payingpost. Here advertiser will offer you to write something about their website and it will pay you for that.you can earn money by affiliate program. for lot of information on affiliate program click on the link of affiliate program.