Transcendental Meditation is the simplest of all meditations and can be learned by any one, of which I personally practice and would recommend to everyone.

Your age will determine which Mantra you should personally use. You should always use the same mantra, not changing it as you get older. The pronunciation of your mantra is not important, so say it how you feels right for you and it may change over time. There is no scientific research performed on if the mantra makes a difference, but you need to say something, so there is no harm in using the suggested ones.

Before starting your meditation, ensure you are in a suitable environment where there are no disruptions or distractions. Turn off your phone and inform others that you are not to be disturbed.
Sit up comfortably, in an arm chair preferably. Ensure you are warm, using blanket if necessary. I wouldn’t recommend lying down as you are more likely to drift from meditation to a sleep state. Place a clock of which you can glance at without moving.

Following these simple steps

1. Take note of what time it is and close your eyes. For about 30 seconds let any thoughts fade, to start the process of clearing your mind. This does not need to be exactly 30 secs, so no need to open your eyes to check.
2. After approx 30 second has passed, start repeating your mantra over and over in your mind.
   Repeat your mantra at a comfortable pace, not too fast not too slow, whatever feels right for you. Ensure you are not to moving you tongue or lips and they are completely relaxed. As you continue repeating your mantra, slowly let go of the clear pronunciation so it becomes the notion of the word instead.
   As you continue repeating your mantra, everyday thoughts will arise and distract you. At some point you will find yourself no longer repeating your mantra. When you realise this, then resume your mantra again. This is a natural, continuous and positive process. You may follow a series of thoughts for many minutes before realising and resuming your mantra. This is natural to have these thoughts and calmly replacing them with your mantra will enable you to release them.
3. Continue this process until a total of 20 minutes have passed (Children under 18 yrs old should only perform for 1 min per year, e.g. a 12 yr old = 12 mins).
   Wait until you feel a full 20 minutes have passed, then slowly open your eyes to check. E.g. If only 10 minutes has passed, then you know what 10 mins of meditation feels like, so continue for the same time again. With regular practice you will become surprising accurate at knowing when 20 mins has passed.
   If you have gone over 20 minutes this ok.
4. Once 20 mins (or more) has passed, you should continuing sitting still with your eyes closed for a further 2 mins. But, instead of repeating your Mantra, simply let go of any thoughts that enter your mind, in an effort to keep it clear.

Thats it…

Perform this simple process morning and night, daily.

While I believe this information should be free, it may still be of benefit to go on one of the TM courses, as you will get the support you may require to make this a daily practice. This is no different to going to the gym, as you can’t expect to go once, get and remain fit, only regular practice will make the difference you are looking for. While the courses may seem expensive, if you can afford it they are good value, especially as the TM organisation put a lot of its money and resources in performing creditable scientific research.

Source of instructions: http://minet.org/mantras.html