So Cat Anderson's advice to practice everything very softly and Schilke's advice to practice everything very loudly are both very correct. Just not for the same individual.
I can tell you what I've done since I attended ITG in Harrisburg which has made me a brand new trumpet player with better tone than ever, better control than ever, far less fatigue than ever, and I'm on my way to a higher range than ever. But I would never suggest that if you (or anybody else) were to follow what I've done that you would find the same positive results.
You want a good tip? Find out about all the literature that's out there, read as much as you can, buy as much as you can, and then start working through it and weed out that which isn't helping and build on that which is working. For you. Not for me, not for Rowuk, not for NickD, not for Maynard, not for Cat, not for Maurice Andre or Chris Martin or Phil Smith or Ignatz Q. Town-Band-Member.
It really does boil down to the two things which have been repeated over and over again: listen to the trumpet players you like (and that implies active listening so that you are thinking about 'how does she do that?') and then practice. Daily.
One thing which bothers me most in the trumpet literature I read is when the people say "do this and you will be better." That's not true at all. It will work for some people, maybe even for a lot of people, but it won't work for everybody.
Take the "Wedge Mouthpiece" as an example -- it's a godsend for some people, but when I was at ITG, I stopped by their booth. Once in the morning and found that none of their mouthpieces helped me sound better or play better than the Bach Megatone 1C I had been using for 15 years or so. I even went back in the afternoon when another person was helping man the Wedge booth. And he had me try lots of the mouthpieces and suggested this-and-that and finally he said "You may be one of the people for whom the Wedge just won't help." I thanked him for his honesty and went on my way. Later that day, with the help of my son (a trumpet major in college) and the trumpet players who were working at the Pro-Winds booth I found that the Laskey 84D made a significant improvement in my playing. I bought it and have been using it exclusively since. And that may well be a large part of why I am playing better than ever. Does that mean that I would suggest to anybody else that they should be playing on the Laskey 84D mouthpiece? No way!
There's only one trumpet player who can play better than you can play that you should really be concerned with, and that's the "trumpet play that you will become." Don't look around at the others, look in the mirror at yourself and you'll see the trumpet player that will be better than you are right now, and then work to become that trumpet player you're looking at.
Reinhardt, after essentially saying that his method will help everybody, does make some very insightful comments: this quote comes from The Reinhardt Routines, compiled by Rich Willey and published by Pivot Publishing, subsidiary of Boptism Press: "If a percentage can be applied to the teacher/student's success ratio, it may possibly be, at most, only 20% on the teacher's side." That means that the student is at least 80% of the success ratio.
The teacher is the guide only, making slight adjustments here and there and opening the student up to music the student might otherwise not have known about, but the student has to do the work.
The same is true of tips -- one person's best tip might send another trumpet player into ruination. Such as me reading about how wonderful the Wedge mouthpiece is and reading about the wonderful people it helped. Without my background as a teacher, questioning everything and analyzing what works and what doesn't, I could easily have spent the money to buy the mouthpiece, sounded worse and imagined it was simply that I wasn't meant to be a trumpet player and quit.
So any tips anybody gives you, including mine, should be taken with many grains of salt.