okay. i'm thinking an Adder for my first. i have cargo, it transfers right?
Transferring cargo works if the new ship has space.
When buying a new ship (instead of transferring to one you already own) then the 'stock' loadout must have enough space.
For an Adder, the default loadout has 6t of space.
The Coriolis website is a great way to check the default loadout and experiment with your own:
https://coriolis.edcd.io/
My golden rule for upgrades is to have at least 2x the ship purchase price (including the trade in price if you sell your current ship). This will leave you with enough money to buy some upgrades and have plenty for insurance.
Going from an upgraded ship to a stock 'better' ship will be a massive downgrade and upgraded modules are generally pretty pricey.
The Adder is an okay ship, but I'd recommend a Cobra III or Viper as soon as you can afford it - they are much better ships. The Adder is bad at combat. The big gun means nothing with its poor manoeuvrability. The main benefit of the Adder is good jump range and decent cargo space. It's the Internet Explorer of spaceships. It's useful for getting you to where you can find a better option.
The Cobra III is arguably the most versatile ship in the game. It's very cheap for what you get, and the upgrade potential is huge. I have an upgraded Cobra with a trade-in price of about 9 million, which is insane since it costs just 0.35 million to buy.
On this subject: PRO-TIP for upgrades!
Find a system controlled or exploited by "Li-Yong Rui" (use the 'powerplay' or Galactic Powers map filter).
His systems have a 20% discount on all ships and upgrades. You do not have to join his faction to get this (I advise ignoring 'powerplay' completely).
His home system is Lembava, which has a decent selection of low-end ships and equipment. If you want a better selection, try
(spoilered since this is not obvious and some people will want to find good locations themselves).
For quick cash, RES bounty hunting (mostly kill-stealing from the system-police) is hard to beat - though it is dangerous. RES stands for Resource Extraction Site, which can be found in many ringed planets. I'd google it to find out more. I'd try it when you get bored of courier missions.
I'd keep well away from "conflict zones" in systems with "War" status. They can be very dangerous for new players (and old ones too!). They might be worth trying in a wing, but make sure you have spare cash for your inevitable deaths.
If you desperately want to be an explorer, the Hauler is the cheapest viable option for sightseeing. It'll get you to Maia or Betelgeuse quite easily. Strip it bare, upgrade internals to D-class (lightweight) and an A-grade FSD, plus a big fuel scoop (best grade you can afford) and scanners (detailed and advanced if you can afford them). You don't need a shield (though you might feel more comfortable with one). You might want an A-grade powerplant, since higher grades protect you from burning up when fuel scooping.
It's probably best to wait until you can afford a Diamondback Explorer if you want to find unexplored systems since you'll need to travel at least 1000 Ly to find any.
I'm currently heading home at about 750 Ly from Sol after a round trip of 10,000 Ly. The last new discovery I made was about 900 Ly away from Sol.
