I'm surprised nobody mentions MIDI tracks. They can serve as click tracks, intonation guides and a lot more. Counting bars is normally easier, and so is changing tempos. Often the composer or arranger will have a raw MIDI file handy. Sequencer software will allow you to calculate gradual tempo changes (ritradandi etc.) or to "humanize" the beats. Other software can make the MIDI beats follow an existing performance, or produce both simultaneously.

Your MIDI file can use various drums for "clicks" and include parts of the music to fix the intonation, if necessary. If your recording software (Audacity...) does not understand MIDI sequences, make it record the output from your sound card playing the MIDI. Moderate sound quality can be tolerated since the track will be deleted eventually.