Start off with a basic Tabata workout until you get used to the intensity/format of the workout. 4 minutes of 20 seconds of work may sound easy, but Tabata workouts are performed at maximum intensity. Indeed Tabata workouts can be 4 minutes of hell with the right exercises. If you aren’t drenched in sweat and unable to talk at the end of the session, then you are probably not sticking to the times, or need more grueling exercises.
After a few weeks, you can play around with the format and change times or add time/exercises. For example, changing the 20/10 work-rest format to 40/20. Another example would be having 4 exercises instead of 2, extending the workout from 4 minutes to 8 minutes. However, it’s a good idea not to make the overall workout too long, however. Unless you are a super athlete you will probably be unable to maintain the intensity required. One final thing to say here is to make sure you warm-up prior to tackling a Tabata workout. The intensity required for these workouts is easy to injure muscles not warmed up properly.