Betting spread

Hi
I am all new to BJ, and i am learning to count.
I am playing european no hole card, S17, double 9-11, DAS allowed.
I am learning the Hi-low system, and my queation is how big a spread i should use ?? i would also like to know at what true count i should raise my bets.
I have been reading about different ways to do it, but for a beginner what would be the best ??

How many decks are being used and how is the penetration?

It's a 6 deck game, but i dont really know what penetration is...

Pene is how deep the shuffle card is inserted - how deep is the game dealt prior to re-shuffle (4 decks, 4.5 decs, 5 decks, etc.) zg