Get yourself up to 280ish light (if you haven't already) to compete in Rise of Iron activities without sweating too much. Complete the main story (4 or 5 missions), then do the SIVA Crisis Strike playlist (320 is fine, doesn't have to be the weekly playlist). Then Archon's Forge once you're at 350-360 or so for the biggest bang for your time. Actual Forge drops will be mostly ghosts & artifacts, and maybe a piece of armor here n there. However, the sheer amount of engrams you'll get will get you to 385 (blue engram decrypt cap) in no time. Don't forget to do daily public events for a free legendary engram on all three characters. I'd stash those until you're at or above 385 because those decrypt up to 390. Once there, you should be raid-ready for the up-to 400 drops from the hard mode raid. If you find yourself needing a boost, all vanguard and faction packages (including QW) drops up to 400 as well so do as many bounties as you can handle.