Those trucks CAME with pretty dang high amp alternators, so you should not be having much of a problem for normal plowing...
For starters, have your alternator tested and make sure it's OK. If it's not doing well, then replace it with whatever the highest amp alternator the parts store says will fit. And have your battery tested too while you're at it! A weak battery will make the alternator seem bad, when the problem is really the battery.
If you don't get a significant run time between the last job and when you shut the truck off, it's probably low a lot, and that kills batteries fast. If you finish a job and are done without much of a drive, at least let the truck idle for 15 minutes or so with the heater and lights off before you shut it down. That'll help to keep the battery happy.
For doing a lot of small jobs with a lot of angling and lifting but little drive time between jobs, you could also consider adding a second battery to help out, or replace your stock battery with the biggest one you can fit in it's place.
The other thing to check is the amperage draw of your plow motor. Older Western motors had huge amp draw compared to newer stuff. That motor should only be running for 1-2 seconds at a time for most plowing, so if yours is exceptionally slow to lift or angle, you have hydraulic problems that are causing you to run the motor way too much, and you need to fix that first.
Finally, technique can come into play as well... If you're lifting the plow all the way up every time you lift it, that takes a lot of power. So does lifting it while you're pushing instead of letting it ride up the bank a little. I let it ride up, and bump the up button for a second to lift the arm, but not necessarily all the way up. That way you're just free spinning the motor, not really having to generate much pressure. And you should be letting go of the lift or angle button just before it stops angling or lifting, not half a second after. Anytime the motor runs but the plow isn't going up or angling anymore, the amp draw spikes really high. Don't do that.
Hopefully something there helps you out!
Chris