Tell me yours! 
I'm glad I had to learn every key and every scale when I studied as well as all the C-clefs. All the early training in different transposing of G-clefs AND to transpose a part at sight. All experience from conducting as well as analytic training as an engineer. Sometimes all those skills on the side is what saves the job, you could of course as well call those skills experience.
Transposing at sight is one of those skills you never know is needed until it saves your job
A method in the beginning to learn could be to rewrite parts or you pick up those skills as you learn to arrange and compose music or you work as a teacher and play parts with your flute-,clarinet--,saxophone-, french horn-, mellophone-- or whatever- students. I think the last experience was what saved my last gig.
A resent experience was at a cermony in a great cathedral this sunday. We came to the church with not much time to rehearse just to discover we had to cover not only our traditional trombone parts in bass clef but also had to read from a score and play parts in G-clef in both Bb and C within the same hymn. All hymns were like that and instruction how to play were on a separate sheet of paper like this:
- verse 1 play the parts
- verse 2 trombones play unison on the melody
- verse 3 only trumpets
...and so on
As we played we had to scan the score quickly to figure what parts in the score to read next to find the melody to transpose and then jump back to our own part in bass clef. All this had to be done at the same time. Not difficult parts but what made it difficult was the instructions were on a separete sheet of paper and the small size of the staffs in a score as well as the fact that first and second parts in a score often are on same staff. Also I need to do ALL this at once and add the obstacle that my eyesight isn't what it once was. In short to get the best result you need to know the melody and play it from memory and guess some chunks of the ongoing part at the same time as you scan the instructions as well as the score to figure out what to do and where to play next. It helps to have been at a few cermonies so you know ALL the hymns also by heart and your abilities to improvise also are tested. Some kind of odd requirements. Not your everyday-gig
Just one example what you need to solve on a gig sometimes when skills in theory and a lot of experience is highly important. The actual music was the easy part. What adds to it is almost no time to rehearse. No point to complain. Just do it if you want to be called next time. From experience I have my own method to 'code' such information into "my part/s", so I was rather fast to transfer all the instructions with a pen. If I hadn't done that I would have been lost because you can not read sentences on another paper at the same time as you are reading and transposing notes from the score on the other paper.Once at another occation I had to play a whole church gig in bassclef in Bb. That was a challange before I realized the part was in Bb. The organ player had done the arrangements and deliberately printed them in bass clef in Bb to help us because he thougt we preferred them that way and since we had no time to rehearse he wanted everything to be as easy as possible to avoid any wrong notes
Bass clef if Bb isn't something you do very often./Tom
