Things to note if you don't know already.
1. Planetary tokens will only get you planetary faction reputation in Forsaken. So turn them all in now so you can get legendary items to shard for legendary marks.
2. On the 28th, whatever element you have on your elemental / heavy weapons will be locked. If they stay elemental. i.e. Hawthorne's shotgun is turning kinetic. Uriel's Gift remains elemental, so if you have a solar one, it will be locked as solar in on the 28th.
I'll try to add more as I think of them. If you have any, please post.