To be honest, I'm not too sure, but I'd advise focusing on upgrading one at a time to start. My suit was the easiest thing to upgrade (finding drop pods by selecting "Shelter" from the beacons emitting orange light), and I'd just grind rare resources to make sure that I have enough to afford the upgrade (first upgrade is free, I believe, second upgrade is 10,000, and each upgrade after that adds 10,000 to the cost, ie, second upgrade 20,000, third 30,000, etc, etc). Secondly, Atlas Pass V1 opens up the door in the space station and it contains a suit upgrade pod as well. The first thing I'd do when I entered a new section is stop by the space station, offload any goods at the market, then open that door and buy a suit upgrade. By the time I got to 48 slots, I had amassed quite a bit of chump change (over 1 million, simply from farming and selling resources like Aquaspheres, Gravatino Balls, and resources like Gold, although Plutonium is plentiful, and can net you some nice profit if you're in a pinch). Once my suit was upgraded, I started looking for a better multitool (I settled on one with 20 slots, but will upgrade again eventually; my current configuration of upgrades is making mining and combat a cinch). After the multitool, I finally settled on a ship with about 25 slots, which I purchased for 1.7 million. I'm doing a few other things first, but I'll soon be purchasing a ship with more slots (probably after I save up about 5 or 6 million units), and then I'm farming "Transmissions" from the signal beacons to find a ship with 40+ slots. It can be overwhelming trying to upgrade all three at once, so Suit > Tool > Ship worked out best for me so far.