Joining triathlon is one thing. Preparing for it is another. So, to avoid coming short on the finish line, you must prepare for it long before the competition starts.
Once you have the desire to join triathlon any time soon, the very first thing that should concern you is the right time of your training. Actually, there is no right or wrong time of training. Early in the morning, late in the afternoon or even on midnight would be okay as long as your body can adapt to your time schedule.
If you choose to train early in the morning the effect would be for your body to boost its metabolism. This is great if you want to maintain your body weight. You burn more calories while training and continue for several hours even you have already stopped.
The best time to train is in the afternoon. You are fully energized at this time of the day for your body has been nourished and hydrated since you wake up.
In case you want to train during midnight, you are free to do so. As was said, as long as your body adapts to your time schedule, anytime is okay.
You have 3 disciplines to hone: running, swimming, and biking. Let us start with running. There are several places where you can improve your running. A treadmill would definitely let you monitor every detail you need. An open ground would keep your session just like the real competition. For you who would run outdoor, one tip that should be remembered is that you must change your route regularly. Doing so would keep you up and about every time.
Stationary bike or real triathlon bike are two ways where you can improve this particular discipline. Again, changing your outdoor route would keep you from tiring so fast.
Unless you have swimming pool at your home, access to train on this discipline is limited. Have a particular time where you can hone this.
One thing that you must remember is that no matter how hard you train, it would be useless if you result yourself to over fatigue. To avoid this from happening, take a rest. Your body will improve while resting (untrue to the common notion that the body improves during each session). Make sure you have a good rest after every training to avoid not only over fatigue but also injury and lost of motivation.