The key to focused mediation is overcoming two interconnected and polar difficulties which the Tibetans refer to as monkey mind and sinking mind.  We suggest meditating in this manner 20 minutes a day.

1) Monkey Mind - mind jumping around
And often, when we still our mind, we might tend to fall asleep:
2)  Sinking mind – falling asleep or going unconscious

Two powerful tools for addressing these polarities are:
1)  Patiently bringing your awareness back to the point of focus and
2)   Remaining senior

Monkey Mind - Bring your Thoughts Back to your Focus
Instead of gritting our teeth and willing ourselves to focus, validate the recognition of your overactive mind and bring yourself back to your point of focus.

Also useful is clearing what you find between you and your meditation.
For example, while meditating on the belly button chakra, we rest our meditation focus on it, and, in the beginning notice what is between us and the belly button chakra.  Then we begin to clear it, so that our attention,  even as we address the obstruction,  will remain mostly on the belly button chakra.

Sinking Mind – Stay Senior
The other polarity is sinking mind.  The technique that works very well is to become senior to it.  As long as you are senior, you will not fall asleep.

Clearing unconscious energy will help with both polarities.  So if you start to fall asleep, throw a bunch of violet energy and begin asking if there is any unconscious energy, and stay senior to it.

Note: The Tibetans and other Eastern teachers recommend to making it more vivid - to intensify, to brighten the meditation focus.  E.g. brighten the belly button chakra. 

Other Techniques:
Sometimes you may even need to turn your attention farther away from your mediation focus while keeping just a little bit on your meditation focus.  E.g.  belly button chakra, may need to clear your 6th so can keep your focus on the belly button chakra

Clear the Reticular Formation.  With staying focused, it helps to clear the focused part of the reticular formation.  Reticular formation is quite a long complex part of the brain stem.  Towards the top of the reticular formation, a little behind and below the midlevel of the ear, there is a nucleus, a center of the reticular formation, about the size of a small jelly bean. 

Also clearing telepathic channels and ears, and clearing and setting your grounding – all of these will help.