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 this means is that if you bet too much, you risk losing all your money. It would be foolish, for instance, to bet your entire bankroll whenever you have the advantage. Your expected value is high, but your risk is unacceptable. On the other hand, if you nothing, you won't win anything but your risk is 0. So the trick is bet the amount which maximizes bankroll growth while minimizing risk.
This is where the concept of optimal betting comes in. A simple formula is optimal bet = bankroll * advantage / variance (where the variance for blackjack is around 1.3). So for each true count, if you know your advantage, you can calculate your optimal bet. Note that the optimal bet grow proportionally to the advantage.
Using the above formula, you would bet 0 whenever you have a disadvantage. This may not be feasible in single or double deck games (they might notice this). You might get away with this for while in 6 deck games by wonging in and out. If you do play in negative advantage situations, the optimal bet calculation becomes more difficult because you have to take into account the additional risk. There are commercial programs such as QFIT's CVCX which perform the calculations for you.
Another issue to consider, since your bankroll may increase or decrease after each bet, you would have to recalculate the optimal bet. Also, the optimal bet is not likely to be an even chip size. Because of this, many players calculate a unit bet size that doesn't change unless their bankroll has a significant increase or decrease. You might read about 1/2 or 1/4 Kelly, which means the unit bet size is 1/2 or 1/4 of the optimal.
Finally, you might be in a situation where you not have a large enough bankroll to justify even betting the table minimum, but if you do lose your bankroll you can replenish it by doing real work. In this case, you might consider your bankroll to be the amount you would be willing to risk over your lifetime. You might have trouble convincing love ones about this.
If you are really interested in this subject, I would suggest reading Blackjack Attack. Also a bj21 greenchip membership gives you access the archives which has many discussions on this issue. MathProf, for instance, has written articles about the effect of taxation and trip expenses on your risk.