So I'm 18, have about $1,000 in stock, and I'm wondering what my investment strategy should be?

Just invest in strong companies. Never trade penny stocks! Only strong, profitable companies. Yes, JNJ, CSCO, and you can take a bit of risk trading other stocks. What you need is information and adequate recommendations. Follow twitter accounts of firms such as AllianceBenstein, ValkCorp, BlackRock, T Rowe Price. They will help you, you can return 20%-30% a year without lots of risks.

lol. Doesn't it get lonely living in your parents' basement? There is this weird species out in the world that you may like. They are called girls. And to better get one, you generally need a horseless carriage, and some money to spend on them (the car and the girl, lol). College also costs money (but should pay off big).

Keep the stock you have if you like it, but give serious thought to having current, readily available money.

P S General Motors was a blue chip stock. So was the old Sears, and the old Kmart, and many others.

Also note: I make 24% per year keeping my credit cards paid off; I save by having no monthly banking fees or overdraft fees, and I save by prepaying for a year's worth of some things (like car insurance) instead of paying monthly. {In the old days I could also brag about saving one stamp a month.}

with only $1000, you should be putting no less than $500 in any one stock trade or the buy/sell broker commissions will eat too much of your profits - stick with Blue chips - most pay dividends also - you'll get income plus safer capital