Choose a nice blogging theme that you think will work from Themeforest - so much good stuff there I spent atleast 3k the last year on templates.
As to jumping into a niche and recommending a number of different products, that's a great way to go which a lot of successful affiliates do.
A major benefit to doing that as an affiliate, and building out a site with good content and recommendations on products, is that over-time it will become a complex and gain trust from search engines. So you will start ranking for product brand names easier (smaller ones ofcourse).
So say for example your website was jordanstrustedreviews.com (even though it wouldn't be that!). You would have a dedicated page for each product under a sub url, for example:
jordanstrustedreviews.com/venus-factor
jordanstrustedreviews.com/ed-miracle
jordanstrustedreviews.com/diabetes-lie
Or whatever your promoting, I'd recommend choosing some smaller products, that have a gravity of 10-30 (so you know they convert), so that you can rank for those products easier if there isn't too much competition.
But as a tip for getting started, don't put your heart and soul into SEO - work on it, but also learn other ways to bring visitors to your website too so your not just waiting for rankings so that you can start earning.
Cheers
