It's saying I have max inventory on wood when I try to pick it up, but I have 0. What do?
First of all, go to the (touch-pad menu) > Crafting > Carry Capacity > ***complete all of these upgrades*** - it'll improve how you're playing the game and also help you out later. Yeah I'm some guy on a forum, at least this time trust some guy on a forum. It will take awhile to hunt/find all of the parts, but every chance you get to upgrade in that menu, upgrade.
Second, go to a vendor, if you don't know where one is or can't find one head to a town/camp/whatever has people in it - look on your compass for a "horns sign" and talk to them. Hit R2 so your'e on "sell" and go through the menus and sell everything you don't need. WHICH IS: On the "resources" screen sell anything that says something close to, but ONLY "sell for shards". Things that say that and other things are useful for trading in to other merchants. Basically, you keep conquering the map and then selling stuff that only says "to sell" - lots of ancient debris & taking out forts will net you these things, and it'll be worth a lot of money.
On the "modifications" screen, unless you're having a great time plugging in mods to low level armor, sell every single green piece. They will never be worth saving.
note: Every single time you're on this screen. Sell every green piece, trust me.
Between the last two things you'll have a ton of money the entire time. Also the first chance you get to buy the purple item that lets you fast travel, buy that and then sell all fast travel packs - **every single time you're at a merchant**
Make it a point to be constantly selling things, and you'll always have inventory space & money. PS - always sell stacks of plants/wood/materials when you have two full stacks of them.
Ok I'm passing out, night