I agree with the comments already posted about how to be a good fireman. It requires a lot of work and cooperation between the fireman and engineer. I have only fired a wood burner and an oil burner but the principles are still the same.
1. know your engineer and his temperment
2. watch how he works (or does not work) the Johnson bar
3. water, it is all about the water. Keep the water at 2/3 glass and try to match the amount of water you put into the boiler with the amount used, better to put in a little a bunch of time instead of a lot a few times.
4. never get behind in the water as you will just pay for it later.
5. don't be bashful in asking the engineer for helpful hints
6. don't ever think you know it all
7. don't sit back and think the fire will take care of it's self, it won't.
8. enjoy the challenge of keeping the steam pressure and water at the designated levels
9. know your engine and the lay of the railroad, ask the engineer if you are not sure
10. Pay attention to what you are doing.
On the Sumpter Valley we get a lot of bad/non burnable wood. Some fireman cannot make it all the way without stopping to build up steam. The good ones fire very hard/agressively and keep the water level high so as not to get behind. They continually put wood into the firebox and water into the boiler, thus they keep ahead of the fire and steam. The other ones sit back and hope the fire and water will take care of it's self.
The most important item:::
TAKE PRIDE IN WHAT YOU DO AND HOW YOU DO IT.
reading some of the books suggested by others is a great idea..