Affiliate Marketing Secrets

So I’m trying to choose my niche for online marketing, but I’m not sure where to start.. I’m a gaming guy, gaming is what I want my niche to be about, but that’s not what I want YOU to suggest to me.
I can’t do a gaming niche, the problem is the amount of space the games take, and the capability to run it. Also the large files.
Anyhow, what are some good niches? Some that many people like, and will download.
Now let’s use weight loss for an example. If weight loss is my niche, what kind of stuff would I upload for people to download?
I’m stuck here, I’d love some help. Thanks.

Recently I’ve been investigating how to be a Japanese teacher in the Australia. To be that, as far as I know I need to have “bachelor degree” first(either in the Au or in Japan)
and Dip Ed(in Australia), a certificate to testify myself as a native Japanese speaker/testify that I have a capability to teach Japanese or not, and experience as a Japanese teacher. These are three main factors I heard.. But I’m stuck in the point that whether the demand for Japanese teachers in AU is high or not/ There are some niches for Japanese teachers there in the AU these days. I wonder if you know recent tendency toward it.. I need some information and if you know some please let me know.. I appreciate your help. Do you know some Japanese teacher out there?