Lesson 1: Know what your investment style is before you start investing. Granted different situations call for different styles, but you should know your core investment style and goals that you're after. I unfortunately didn't really plan this out but have settled on focusing on dividend growth stocks with the occasional pure growth.
Lesson 2: Be wary of small lot purchases. I funded my brokerage account and was ready to trade as soon as the money hit the account. My first lesson learned is to be wary of commissions. I decided I wanted to buy some EOG Resources (EOG) and felt that $94.50 was a decent price given they're substantial acreages in some big name domestic shale plays. They were able to get in early which means cheap in the Eagleford shale and have had unheard of production from the wells they've completed there. Unfortunately being a beginning investor I didn't have much capital to invest and so I had to make some decisions. I was ready to own the world through my investing and didn't allocate nearly enough to the shares I purchased. I spent nearly 1/3 of my capital at the time to purchase 4 shares at $94.50. Not smart. The shares had to appreciate by 2.1% just to break even to my new adjusted cost basis. Not to mention that to sell I have to dish out another $7.95 in commission meaning the shares have to appreciate a further 2.1% for me to truly break even. So my lesson has been learned.
Lesson 3: Have the courage of your convictions and purchase more shares to average down. I truly believed that EOG would climb in value. Unfortunately the Euro mess arrived and pushed the shares down to the low $70's, I think they even touched the upper $60's. I thought that my belief's were right but I was still a 2 month old when it came to individual stock picking. My capital had grown through new investments but I still didn't have enough to commit to a further position. So instead of averaging down to a cost basis in the low to mid $80's or lower depending on how much I wanted to invest I'm sitting on around a 5.4% gain instead of the 20-30% gain that I could have been at. So lesson learned is if the stock goes down and nothing has changed think of it as a sale.