Person A has been beating person B by 15-25 points, What should B's handicap be?
Person B has been beating person C by 30-50 points, What should C's handicap be?
If A plays C, what should C's handicap be?
http://senseis.xmp.net/?JewdansHandicapSystem mentions states each stone is worth 12 points (territory), does this sound right?
That works out to: B getting 1-2 stones against A C getting 3-4 stones against B C should get 4-6 (5) stones against A
Sound about right?
If you play a lot, count your wins. Whenever one player is three wins ahead of the other, change the handicap and reset the score to zero.
This is the traditional way to manage handicaps when players play a longish series of games. Another way that might be more efficient in getting started is to start with some handicap (or even) and then change the handicap after each game, up one if white wins, down one if black wins. When the handicap settles down to oscillating up and down then institute the "lead by three" policy.
One thing that is important to know is that when there is no established rating system in place handicaps don't follow any specific rule. It could easily happen that B takes two stones from A and C takes two stones from B but A can't beat C giving three stones. You'd think that A would give C four stones but handicaps often depend on the specific players and don't work linearly.
Yes, One handicap stone for each 10-15 points of victory has worked well for me.