So I'm pretty new to playing also. I've just been doing simple delivery missions in my stock Sidewinder but my biggest paydays have been when I've gone to a nav beacon and did some bounty hunting. I have about 120K saved. My plan was to save around 400K and then buy a Viper and kit it out with better weapons. Reason I was thinking this is that I want try some of those combat missions because they have quite high rewards but I know I can't do that until I get a better ship. The Viper looks like a decent fighter. Although reading this post I'm now torn on whether I should upgrade my sidewinder a bit first to get a better FSD. Or do I go the Hauler route. Or do I wait and save more and get Cobra. Argh!? What to do?
The one piece of advice that's nearly always true in this game: don't buy too soon. If you buy a Viper or a Cobra, make sure you have enough for insurance, plus maybe a little for upgrades straight away. And you'll need seeding money if you want to do any trading or any missions that involve purchases. The Viper is pretty much a 100% fighter, the Cobra seems more rounded in its roles.
The Cobra might be a good call if you're not sure what you want to do yet. If you know you want to go bounty hunting, then go for the Viper. Or if you want to make loads of money so you can get a much better craft later, maybe trading is quicker (though perhaps more boring?).