Standard rule, only invents in stuff that you know something about or are willing to spend some time learning about. I made a nice 20% profit on HDTV and BRLC in the last two weeks and 40% off SIRI in a week when they announced that Stern's old boss from Viacom was going to be the new CEO. That one was luck, i managed to pick up the stock 3 hours before the announcement and it made a big jump over the next 3 days. Right now I've got some money in a biotech firm NUVO, promissing drug in their testing stages but it's a long term hold for another year or so until they actually get somehting to market.
If you want big profits it takes a decently high amount of risk and paying attention daily, and you have to be able to live without the money incase you guess wrong and lose it all. A lot of the short term profit are to be made from playing the news adn not the actual financials or technicals of the companies. For long term stocks i always go with a companies technicals, are the actually goingt o make something that is needed and will it sell and will someone else beat them to market or not.
Other fun is to play standard cycles, retail for Christmas season, automotive for spring and summer, home builders in summer to early fall. Many types of stocks have a standard cycle when they always go up and down and you can make a little profit from that cycle, not great but good.
(cool)