Get a bigger Trunk, carry bigger Junk
Cargo space is everything. The starting sidewinder (and eagle if you pre-purchased) can carry up to 4 units but that’s not enough for the future. If you’re serious about trading, get your hands on a Hauler or Adder asap. Why? Well because they can be equipped with more cargo racks than the traditional starting Sidewinder. There can be almost no doubt that in combat the Sidewinder wins but when it comes to buying and selling goods, the two aforementioned ships are the way to go.
It can be tempting to upgrade more nimble or powerful combat vessels up the wazoo. They can be used for piracy and generally have more in the way of opportunities to protect your cargo. That being said, if you’re only travelling between a handful of space ports you’ve already discovered then you’ll likely be safer. Foregoing protection for a bigger cargo hold might sound a little crazy but the world of Elite: Dangerous isn’t all that dangerous.
Being able to carry more will also reduce your cost-per-unit in comparison to using a combat-focused vessel. After all you are trading here, anything that even slightly cuts into that profit is a bad thing. Carrying 12 units of Gold instead of 4 doesn’t just cut down the fuel cost per unit however. It also means you’ll be earning money quicker. The allure of a bigger ship or a combat craft is a hard one to mask, so getting that credit balance higher as quickly as possible can give you more freedom.