Basic Leader Formula - A.J. McClane's
AJ provides this simple rule of thumb for leaders - 60/20/20
meaning that the butt = 60%, taper = 20%, tippet = 20% of overall length;
Butt compounded once again 60/40 of length,
tippet compounded into two or three sections,
Therefore, for a 9 foot SWFF flats leader with 12# flourocarbon I use: 38" of 30#, 25" of 25#, 11" of 20#, 11" of 15#, 22" of 12# flouro.
For sinking lines and bigger flies I use 40# butt and taper down to 15# tippet.
Long summer - same as flats but with three-part taper down to 10# or 8# tippet
Winter sinktip leaders of 4-5' in length similar to SWFF sinking w/ 40# butt down to 15# or 12#
Dry line - 20# butt full compound down to 6# for streamers and 4# for larger dries, 3# or 2# for midges, etc.
These are all rough overviews using maxima spools in sucessive line strengths, which makes up the bulk of my leader strategy.
Anything fancier or finer I buy.
What about you?