.
Short meditations are good too....
The VijnanaBhairava is one of the foremost manuals of enlightenment in the Tantric tradition.
It have 112 dharana's (meditations), that can performed for a few minutes or longer, several times a day...
This can flip your Consciousness totally...
http://www.shivashakti.com/vijnan.htm
Some of my favourites:
Dharana nr: 83
"83.
Contemplate that the same consciousness exists in all bodies."
nr:91. Whether outside or inside, Shiva is omnipresent.
92. Every sensation is an expression of pure consciousness.
106. Look for the I which exists in all limited "I’s"
And this one is great...
108. The whole universe has the reality of a magic show.
69. Concentrate on one’s own self as a vast unlimited expanse.