Here is the how to hold a brush. My hand is way back at the end of the brush opposite the furry part. If you hold the brush up at the ferrule you will not develop good handling. This is of the very utmost importance. I see students in workshops doing this all the time.
HOLD THE BRUSH AT THE END WITH NO HAIR ON IT!
Stay back on that brush. Holding it like a pencil, up at the ferule ( the shiny part) makes crabbed and "short" stingy looking strokes. This will absolutely destroy your brushwork!
Above I am pulling a stroke to the right. I can touch the brush to the canvas and take it in any direction. Practice this until you can too.
Here is the stroke going to the left.
Here I am pulling a stroke upwards.I just turned my hand so the heel of the brush faces the sky and pull the stroke in an upward direction.
This is the one that is a little different. I have flipped the brush over in my hand using a really cool looking professional gesture that looks like I know exactly what I am doing. Then I pull the stroke downwards. This is the only time I turn the brush in my hand to a different position.