My totally un-educated advice is to Stick With C for reading! At least
initially. Reading a score is simple in the key of C because then each
note is played at the pitch it is written as. Other keys use b or
cross marks to imply that a note written as a certain pitch has to be
transposed when played.
This is a bit unclear Per. I think what you are trying to say is that, while written music doe NOT require that you "transpose when played", it does ask that you remember which notes are play as Sharps or Flats (b's or #'s). The first bit of notation on any stave of music is the treble (looks like a f) or bass (looks like a C) clef. This tells is it played above or below middle C and WHICH NOTES are played.
the next is the time sig.. no prob there usually drawn one note above the other.. and THEN... there is a signifyer of WHICH sharps and flats should be played throughout... this is basically saying what key the piece is in.
Markl