I think it comes down to consistency and not posting too much content. Find products that are highly sought after, or items you could see selling fairly well by promoting it on your site/youtube. If you have a blog, I say post 1 product a day, or every other day. Let the product sit and collect clicks, because there's always a chance you can see some sales come in.
I think the mistakes most people make, is to promote too many things at a given time. It's fine to do one or two posts a year listing a ton of stuff at once, maybe it could be Christmas gift suggestions or something. That could work. But some people just spam new products every minute they can, and that isn't going to work that well.