Crafting opens up once you are a few missions in- for the resources leveling up scavenger will get you more resources but the most rare items are rewards from associates (side missions) once they are completed.

If you do all the side missions you can unlock level 10 weapons/Armour etc before lower levels which are mission rewards in the main story line.

I've been ignoring the main story and concentrating on the side missions
I do that on most AC games

Good fun setting my Rooks onto the Blighters

I've been playing it for a while now that I have my new monitor
I tend to do the side missions first before playing the main game which means I've conquered most of Auld Landan Taan with out the rope gun thing :/
Really good game and looks great on the PC

Luckily I haven't come across the Phantom Raspberry Blower yet