Instead, you should learn to read the music on the staff differently. I would strongly advise against either of these methods. I'm seeing suggestions to either relearn the fingerings on trumpet or just mentally calculate the transposition of each individual note while playing. If I'm playing a horn (F) and need to read an Eb horn part, I need to move F to Eb, which is down a whole step. If I'm playing Beethoven 9 (for trumpet in D) and all I have is a Bb trumpet, I need to move from Bb to D, which is up a major third. You're in Bb but you need to be in C, that's up a whole step. But which way? The way I remember it is to move your instrument's key to the target key. That's a difference of a whole step (major 2nd). You have a Bb trumpet, and you're trying to read concert pitch (C) music. Knowing your scales so that you can transpose whole chunks at a time rather than each note individually helps a lot. You just mentally move each note by the correct interval. I've been playing in orchestras on trumpet and horn for years, both of which often have to deal with odd transpositions, and nobody learns new fingerings or employs clef tricks. I think a lot of the respondents don't actually play trumpet, or any kind of transposing instrument. I'm sort of disappointed in the answers here.
