Save the titan blood for weapon upgrades, and go for gemstones early on because there are a few functional things to buy with them before they become the currency for cosmetics. The broker will always have one unique deal after each run so it's worth checking every time.
Also, if you're using a controller the trick with the fishing is to go by the visual indication and not the controller vibration. It took me a long time to figure out you can get a 'perfect catch' if you hit it right on and produce rarer fish/items.
You bow to no one,
azuarc