I have only been investing in earnest for the past year and a half, after having gotten into the idea after catching (and subsequently) becoming hooked on "Mad Money" on CNBC. My first ever stock purchase was one share of AAPL back in 2001, before September 11th and before the iPod. So, that is my biggest win (percentage-wise) to date, despite being such a small "holding."
The rest of the portfolio is made up of a combination of my picks, and several that I have gotten from Jim Cramer. While I am still a novice, I must be doing something right, because Jim recommended some of my personal picks (i.e. Incyte, Avid, Apple, Amgen, etc.) after I had bought them. I have gotten some big winners from Jim, most notably Zoltek and Foster Wheeler, which have both more than doubled since I bought them. However, I have also had some of Jim pick's not treat me as kindly, but in fairness, the majority of the ones that have me in "the house of pain," are speculative plays, and I was warned about that. There are a few that I should probably cut my losses on, but I am foolishly stubborn.