I think many can relate to both experiences.
another clue, with QQQ (and SPY too) the commish is eating a lot of your profits and increases losses.
On the other hand, when trying a new market or strategy, it's really advisable to try small size. Not too small either.
A rule of thumb, try to trade a size where the loss per trade will not bother you too much (maybe just a bit). This is because the important part at this point is to concentrate on the plan.
And regardless of experience, if you trade above the loss size you can feel confortable with, you will make it much more difficult for you to make money.
With more experience and capital, you can handle bigger losses in $, but probably not in %. Many who tried, including market wizards, are doing something else now.
tntneo