Quite easy really my friend, buy lots of cheap (useful items) that will have a big audience and demand, even if it's something really simple, you also don't want to make extreme high profits from such items, instead if you buy something for $8 then sell it at $9-10, this will give a reasonable price for an item in high demand, and will get you a lot of quick feedback, especially since it's not expensive, also try get a high quantity of the item, if you think it will sell well. Good luck my friend, and keep us posted on your progress