To explain it more efficiently that what is a niche market? lets us take this example. If there is market of tomatoes in which there are big and small rotten, fully reaped etc various types of tomatoes coming from all over the world and all are mixed. There then it will be your niche market if you specialize in selling fully reaped, small red Australian tomatoes for an instance. Thus since you have only a specified variety available at your counter automatically it will attract more people towards your market because you have a specifically sorted out product in your market.

Your best affiliates are unlikely to want any help from you when it comes to selling your product or service; they will most likely be experienced marketers themselves and could probably teach you a thing or two about selling online. You can't rely only on experienced affiliates, there will be a considerable number of people who will join your affiliate program who are inexperienced in some aspects of internet marketing and the onus is on you to help them in any way you can.