How To Keep Score in Ladder Golf
Each step of the ladder is worth points. The top step is worth 3 points; the middle step is worth 2 points; and the bottom step is worth 1 point. If you get all three bolos to stay on the ladder, you get an extra point. You can also play with a rule where you get an extra point if you get one bolo on each step of the ladder. The design recommended by this site actually color codes the steps to add further clarification as to which one you are aiming for (ie - "aim for the red one").
Note that some people will play with or without a Bounce rule. Many times someone will toss the bolo and it will land before the ladder and bounce up onto a step. I personally prefer to play where this is allowed, although some people prefer to not allow this.
Scoring Variation - Cancellation
An alternative scoring technique when playing with only 2 teams is to cancel out each others score. If both teams land a bolo on the same step, those points would be cancelled out (thus no bonus points would be awarded either).
Cancellation example: If John lands a bolo on the top ring (3 pts) and the middle ring (2 pts) and Steve lands two bolos on the top ring (6 pts) and one on the bottom ring (1 pt). In this situation, John would end up with 2 points (both from the middle step) and Steve would end up with 4 points (3 from the top step and 1 from the bottom step...no bonus point is awarded).