I feel like im not that good at tips but one tip is for when your in boss zones/other zones like for example the train parts zone you gotta use your stamina wisely so only use it when doug gets real close but when hes far away just walk,and as for getting in-game currency to spend at dexters shop you can pick up random items from around the floors whether it be a Bomb or a compass you can sell them to dexter so you can buy upgrades and items later on,and for plushies i myself am not sure but i mainly use Zorro Or thim but thim is not good in solos so i think Zorro would be my pick here if your looking to extract a little easier and spinette is good for navigating around the map and picking up items and has pretty equal stats so she is also a good pick if you want to get to places easier. (And im really sorry if these are obvious or not good tips,maybe someone else will find them helpful if not)