REST
Make sure to get enough rest. You will need to get to know your body better. If you're feeling drained and depleted of energy, the first thing to look at is the amount of rest you're getting.
A general rule is to aim for at least 8 hours of sleep per night. Some people require slightly less, some people require a little more, remember that the important thing is to keep tuned in to your body and adjust your sleep pattern appropriately.
Without adequate rest, you will definitely not maximize your muscular and cardiovascular conditioning since cutting out rest time means that your body cannot recover and repair properly. Additionally, not looking after your body by resting sufficiently will make you more susceptible to getting ill.

NUTRITION
Nutrition is vital to recovery.
You have to give your body the right kind of nutrients at the right time to allow it to repair cells, building up your muscles and conditioning your body.
It is very important after you've been sleeping all night to re-fuel your body for the day ahead. If you don't put fuel in your body when your tank is empty, your body will start breaking down muscle for the energy that it requires.
Another obvious time to eat is prior to your workout. About an hour to an hour and a half before working out, eat a moderate carbohydrate, low protein meal to fully saturate your glycogen muscle stores. Rice, pasta, crackers etc are useful to include in this meal but there are many alternatives.

Another critical time to eat is post-workout. Aim to consume some carbohydrates within the 30 minutes prior to your workout. You need at least some type of carbohydrate to start replenishing your lost glycogen stores. Some good examples are fruits, sports drinks or energy bars etc. Fluids are absorbed faster then solids, so if you decide to eat something, drink some water to aid digestion.
Also don’t forget to get some protein when your muscles have been worked hard. Protein is the building block for the repair of your body. Your body must repair muscle fibres to form a stronger body after the breakdown of them during your training. Optimally, you need a meal that contains 3 grams of carbohydrate for every 1 gram of protein.

STRETCHING
Stretching is an important recovery technique and making a habit of doing it will prove to be very beneficial. Before heavy exercise, stretching helps to improve blood flow to your muscles preparing them for the activity ahead. Post exercise stretching helps to remove the lactic acid (the by-product of energy production) out of your muscles. Lactic acid build-up is what causes muscles to become sore after anaerobic training and removing this waste product will help reduce the next day muscular aches and pains.

SUPPLEMENTS
A variety of supplements can help your body recover after a strenuous workout. They range from electrolyte / carbohydrate replacement drinks, meal replacement drinks, protein drinks and the numerous different kinds of energy/protein/replacement bars.
It's almost impossible to get good nutrition without having some kind of "easy fix" supplement at least during those inconvenient situations.