Have been investing in the stock market since 1995. Stopped about 2002, and didn't get back in until late 2010. After choking on silver speculation, I decided, back in August of 2012, to go strictly (well, almost strictly) with my old bread-and-butter, biotech. Have done very well since, TG. My strategy is to go with companies (15-20) that have one but preferably several intriguing treatments (drugs or devices). Next, I won't buy companies with significant debt, and usually won't buy companies short on cash or with burn rates that make frequent dilution likely. I also use market cap to judge obvious things like up side and market interest, but also clinical vetting (a la the Feuerstein-Ratain Rule), and how much management is drawing in salary vs. market cap (i.e. I avoid firms that seem to have avaricious leaders). And of course, I do like to see which companies have binary events on the horizon, though I don't do a lot of timing per se. But there are opportunities to buy as well as times to sell before such events, depending on the various clues given beforehand.