Advertising is an art and a technology at the same time. It has potential to generates a good money. Now the question is why more than 3 advertising platforms will be harmful?
1. Bad user experience:
A good user experience should always be your first choice. If you provide good user experience neat and clean interface then it is more chances that your visitor will become loyal to your blog. Adding a lot of ads will create more confusing and make your site ugly. Suppose you are watching a movie on television and just after starting there is a 15 minute commercial break. Will you watch the commercial or try to move to some other channel. It is more chance that after a minute or two you will die to change the channel. The same applies to Websites. A blogger can’t live without monetizing their blog on the same time number of adverts will lead move your visitor away.
2. It will make your site slow:
Well a slow site will definitely be bad not just for your users but also for SEO reasons. Nowadays, Site speed is an important factor for SERP. Even a single interest based ads causes to much dns lookup and insert a lot of DOMs and content. If you go for more than 2 contextual ad platform then it will slow your site remarkably. This will cause loss in search engine position.
So it will be better to make a balance between all and limit your ad platforms to two or maximum three. You may choose something like this: Google Adsense + BuySellAds +
Infolink s. Do not take seriously about the company i suggested. I mentioned their name for only convenience. I suggest for One contextual Ads (like Adsense), One affiliate link or direct sell of your ad space plus in-house advertising.
If you have enough good contents you will definitely get some visitor and in some day a few of them will be your regular HAPPY visitor and a growing community. At last you will see you have more than expected earnings.
So, Go ahead and make some money..
PS: Any in link advertising like infolinks is bad for UX. I no longer suggest you to go for such platform.