betting spread

I just finished reading professional blackjack. it did not contain much information on bet spread. I will be using the high low system of counting. I am just learning so i will be playing at a $5 table. i was wondering how many units i should bet as the count increases. i do not want to "overbet" since wong says that that could work against you in the long run. what exactly is considered overbetting. what size of bets begin to attract attention from the casino staff at a table like this. i figure that only playing a $5 table they probably wouldnt even care if i was counting, but regardless i dont want to attract any attention.