I have played trombone for 4 years now, and have recently picked up the euphonium and trumpet. However, as you well know, they are A LOT different. First off, i cannot read treble clef, which has proved to be a problem (working on it), however, my real problems are range problems. I know range takes time and practice to develop, but i was just wondering if anyone had any advice for immediate range and/or tone quality. Thanks everyone !

there is no simple way to instantly get amazing range and sound quality! the best way to help with sound is long notes and lots of them, lip slurs will also probably help your tone quality as well, i hate lip slurs so i play dominant 7ths instead and slur them. lip slurs will also help your top range as well by sluring from say a bottom c all the way to the top of the scale scale withought changing your lip position is really good, it may sound strange but playing a lot of very low notes will also help your upper register by relaxing on the lower notes you are more likely to relax on the higher notes, which will help the higher notes, personally i have found that that one particular exercise has helped my high notes in the arban it stars on a f and goes something like this F G A G A Bb A Bb C etc up to top A. i would recommend getting an aurban, if you dont already have one, i have found it on google books you may want to have a quick look

hope iv helped

get a james thompson buzzing basics book and do those exercises every day