I've made several tarps, starting with SilNylon, but switching to SilPoly. There is not much difference working with either, but the SilPoly should be longer lasting and not stretch as much wet. I hem the edges and sew Grosgrain ribbon loops on for tieouts. Where I have seams, I often sew extra tieouts on. Depending on the use, I often sew a strip of Grosgrain ribbon into the hems on the edge. It adds strength to the edges and allows me to pull the tarp more taut.There should be plenty of plans online. You don't need to use one of these plans, but they can give you some insight into why things are made the way that they are. Long hems and seams in lightweight material are not easy for those of us with limited sewing experience. That's the main reason that I use Grosgrain ribbon in mine, it adds bulk and helps to keep things straight.