Scout1 adds some nifty buffs and tricks. Ranger2 would only make Barrage and Steady Aim slightly stronger. Barrage gets mostly replaced once you reach Fletcher, and Steady Sim still only lasts 10 seconds.
Flare Shot is a good AoE DoT (albeit small AoE radius) that can melt a boss or a mob of foes. Flare Shot is a poor man’s Magic Arrow, so once you get Magic Arrow, you will almost never use Flare Shot again. Also, Flare Shot cannot hit flying enemies, including flying bosses. I got 4 Flare Shot so I could max Cloaking and Camouflage.
I love Cloaking because it’s great for running places. I like to explore maps way higher in level, and Cloaking with the speed attribute lets me sail through those maps.
Flu Flu and Camouflage have their uses. However, I have not found myself using those often. 1 Flu Flu lasts 8 seconds, so 1 is plenty enough.