It will come as no surprise to hear that, in order to race faster, you need to train faster. Training with a race-specific plan is the best way to do this (find plenty of free, downloadable options at womensrunninguk.co.uk/training/) but you can also create your own training schedule using these simple sessions. Aim for two speedwork sessions a week, with a break of at least one day in between (you can use this either to rest, cross-train, or to do an easy recovery run).
THRESHOLD RUNNING