All climbers quickly reach a plateau in their abilities where they are limited by finger strength. A regimen of workouts with a hangboard is the generally accepted way of making gains in this area. The Rock Climber's Training Manual is the seminal work on the subject and has detailed instructions on the process.
A core tenet of a successful hangboard program is rigorous record-keeping. Traditionally, climbers have used a stopwatch (or interval timer app like Tabata) and either paper or spreadsheets. Hangboard provides a single interface for planning, executing and analyzing your hangboard journey.
Hangboard is available now for for free in the Apple App Store.