What should I be doing after each outing?  Fresh water but possibly hitting brackish water from time to time.

Nothing really in freshwater, but in the brackish water, you might want to hose it off with freshwater after each use.  How big is the motor? Can you put muffs on it and connect it to a hose to run it with freshwater?

If it has the flush out on the back of the it make sure you use that. That'll get the salt and any sand out.

If your getting into Brackish water I would definitely flush that motor after each trip. I learned a lesson the hard way a few years back when I had to spend some big $$ to re-do the heads on my Evinrude plus replace the sensors and thermostats on each head. I am in brackish water most of the time on my home water and I always flush mine after EVERY trip. Some days the salt content is pretty high and better safe than sorry.

I also do a wipe down with Bass Boat Saver on the entire boat/motor.

Shortbasser

kind of a side note, but with the muffs on you may not get water to come out of the telltail. you know the little stream of water that jets out. this is normal in most cases because there is not enough water presure that gets in there to fill the water pump. if you use these and see steam or hear warning bells go off turn the motor off immediatly and check the water pump out. also a good idea to replace the water pump every three to five years. Just my opinion.