Here's a method for creating custom expressions that I'm seeing good results with: let the self tune run determine which factors are most important. chose the ones with double digit multipliers to create an expression and of course you can add anything else you think is important. this expression will now amplify the best factors for predicting the outcome of this type of race. I have 4. one for dirt sprint, dirt routes, turf sprints, and turf routes. seeing a lot of winners picked 1st or 2nd using this race specific expression.
