In my experience, there’s a lot of work to be found in the health and beauty niches. But really, if you’re lucky enough to find a regular client, any niche can be profitable. You can get some clients in the automotive niche that are really good, some in the pet niche as well. Electronics are great too, if you find a client that has an Amazon Affiliate site and needs a lot of content. Basically, you just have to figure it out for yourself. If you provide a great service, you’ll get returning clients, which will make your freelancing career way easier, and it will allow you to specialize.