I AM ACTUALLY referring TO PENNY AND LESS STOCKS, I WOULD LIKE TO KNOW WHETHER I SHOULD WORRY ABOUT LIQUIDITY WHEN TRADING 30-40k SHARES AT A TIME???!!!
Find your own niche in the market, find your edge....I know profitable traders that trade very thin NYSE stocks (80,000-300,000 shares average daily volume)....I personally like stocks that trade over a million/day, but I occasionally trade thinner stocks....I've found that you have to be much more patient with thinly traded stocks, and I'd be wary of placing stop orders in thin stocks.
if you really want to "trade" a stock and not invest in it, then obviously you want some volume going on and when you sell you don't want to be taking out the bid as a small timer.