Trading products among spaceports is a commerce that can be profitable for pilots of any level. In its most basic form, trading is simply a matter of buying a product at one spaceport, and going to another that will buy the product for a higher price. There are BUY and SELL commands at each trading center to accomplish this.
Your first activity after securing a ship with a decent amount of cargo space (Remember that fighters and taxi ships can't ferry cargo or salvage. The best option will be either a cargo hauler or one of the transport class ships) will be compiling a list of which ports buy and sell which products. word of mouth is a quick option, ask a friend or your alliance if they're willing to tell you about any good trading routes they know of. Otherwise, you'll want to manually visit the trading centers in local spaceports, and use the LIST command to see what they both buy and sell. Once you've found a route, you'll have to actually haul the product to find out how profitable it is. Most of the time the further or harder it is to get somewhere, the more profitable it will be, but not always.
Once you've found your route, BUY, choose the ship you'll carry the cargo on (You'll need the title on hand), the product you wish to trade, and the amount. Some products are bought and sold in units, so you might need to do a little math to figure out how much your ship can carry. From there haul the cargo to the destination you found to sell, and use the SELL command.
Buying and selling products alters supply and demand. Thus, you will see prices fluctuate over time. If a trading route becomes overused, it will eventually become unprofitable. You should be flexible and always in search of new trading routes.
Some of the most profitable items for trading are not quite legal. These include illegal drugs (quartex, cyrex, haze, betakezamine, and xanadine), military hardware, and harvested organs. Legality of cargo can vary from space to space, harvested organs being legal in League space but not anywhere else. If someone scans your ship and finds illegal cargo aboard, they have the option of attempting to capture you in order to receive a bounty. See HELP BOUNTY for more information.