I found the best thing to do is all your bounties everyday and as much strikes as you can. Once you hit rank 3 (and each rank after that) for vanguard rep you will get a commendation. With these plus your tokens you can buy the purple pieces from the vendor. I'm 29 now and haven't done any raids yet. It's a grind but I found this an easy way. Once you get these pieces then you will have to start farming the materials on the planets to upgrade them to get the most light out of them. That's just my suggestion, someone else might have a different opinion.