I reed for GHB in A and often transpose tunes with a G tonality.
To go up 1 tone (G to A) just add 2 sharps (or subtract 2 Flats) and rewrite a tone higher. Sharps and flats act like + and - and cancel. Bb up one tone is 2b+2#=0, C and similarly to go down a tone subtract 2#(or add 2bs), E to D is 4#-2#=2#.

PP