Get a good teacher, if you can. In the meantime, pick up a good beginner book. Getchell is excellent. Take it slow. Remember to rest as much as you play. Always warm up by flapping your lips for a couple of minutes without the mouthpiece. Then buzz with the piece for a while. Then plays some long first line Gs with just air attacks.
A good book to augment your Getchell is called "Flexus," by Laurie Frink. It's based on the Carmine Caruso excercises, which emphasize that trumpet playing is basically a matter of building muscle response. Figure out a good practice schedule for yourself and spread it out throughout the day if you can. I use a digital timer so I get in three or four chunks of playing a day. Start with ten minutes and add a minute to each chunk until you're up to 30 minutes.
Remember that the key to playing effortlessly is relaxing and using plenty of air. Oh, and be sure your horn is clean. Bathe it in the tub every few weeks with warm water and dish detergent. Use a leadpipe swap or brush to make sure it's squeaky clean. If it's not playing will be a lot more difficult.
Finally, remember that it's all about the sound. A big, round, warm sound trumps high notes and fast notes every time.
Good luck, and good playing!
