Pick a market, build a model, keep records
Most serious bettors specialize. They pick one sport (or one bet type), build a structured way of estimating probabilities, and keep meticulous records. Without a record, you can't tell skill from variance.
Review, don't relive
Weekly reviews focus on process quality, not outcomes. Did you bet your edge? Did you size correctly? Did you avoid markets you don't understand? Outcomes will follow.