I am thinking that before you flip any site is study at Flippa, or where ever you flip sites, how their site looks and what types of sites flip most successfully. Check out designs adn layouts of sites and what articles and items are in the site. Do this studying daily for maybe a week or two, whichever fits your pace. Take note of what is more popular than the others and jot down the top 5-10 categories and niches that you see going for good prices. If Flippa, or fee-based marketplaces, AFTER your lurking and studying for the one/two weeks, THEN sink the money into membership once you have one site developed after studying. If you can, you could try BST area. I don't know what your preferred place of sale would be. You could try this.