I'm Pretty New To Investing - Any Advice?

I'm not a pro at buying and selling stocks and to be honest, I don't have a lot of funds to invest either. I set up an account with TD Ameritrade, mainly because there is no minimum balance or investment requirements and began toying around with their ThinkorSwim platform in paper mode (simulation)...

In any event, I just bought 6 shares of SIRI (Sirius XM Holdings Inc) stock this morning and at close today, I made $0.06. I know that isn't much, but that I actually made money my first day makes me ecstatic. I picked SIRI because it is selling for under $5 per share, has stability as a company, and invests a ton on marketing (there isn't a week that goes by without me getting at least one piece of mail from Sirius radio), not to mention they have contracts with most auto dealerships around the country.

I selected dividend reinvestment on my account and am going to be investing about $25 every week. I'd like to ideally buy around 100 shares of stock per company and have stock in a few hundred companies. I'm thinking of focusing pretty heavily on natural resources...

Luck certainly plays a role, but so does keeping abreast of market news, trends and strategy. Warren Buffet has made billions in the stock market and I guarantee luck is only partially responsible.