Buy coke and amaretto in Chicago, travel to Baltimore and sell it, buy glue and beer in Baltimore, travel to Chicago to sell it.
Each item you buy and sell will count as a single rank up (so if you sell 10, it's worth ten rank ups)
When you have a rank up from it in your status screen your box beside booze or narcs will turn from green to red. When it is red, any buying and selling of booze or narcs won't count. I'm not sure if you need only to buy, or to buy and sell that batch in order to trigger the color changes, or if it is totally time based.
At any rate, even though it is more difficult it helps you rank faster.
J, did you get the invite from the family?