Listen to as much music as you can!
Some extracts from my own brass quintet Mardi Brass can be heard here.
You could spend a lifetime exploring trumpet playing on YouTube, but here is a small selection to get you started...

17th and 18th century repertoire on the natural trumpet:

Standard classical repertoire - extrtacts from the Haydn and Hummel Concertos

With apologies to Haydn, here is my own jazz version of his second movement, played by my good friend James Stretton (check out all his other movies on YouTube):

Arutumian's Trumpet Concerto:

Some amazing flashy stuff:

Some great jazz playing:

The amazing Mnozil Brass:

Listen to Paul Mayes playing the Arban Studies on cornet - here is No.1:

If you have a brace, check this out:

And finally, do plenty of practice so you avoid playing like this: