I certainly hope that you hide your size and show only a few hundred shares instead of posting a "100". While size might not move QQQ's, tape reading often henges upon "presuming" that size like that means MM's or other hidden size-traders. If 10,000 shares in QQQ's represents your total turnaround average shares, then perhaps you should tune into the other "scalpers" and see their methods, and whether these can be adapted to your style.
One of the basic rules for all trading is to never let someone "take you out." Always "initiate" an order, hit bids, take out offers...etc. This is fundemental... Don
As in the market, there really is no definite answer. Use a "blended" approach. Give 5000 away and put on 5000 to your advantage and let them come to you. What is your style or trigger in the market for an entry point?
That might be your philosophy, Don, ("always initiate") but limit orders do have their place. In fact, you use them yourself in your open only orders. You're not initiating there -- you're letting the market come to you if it want's your liquidity.