Never buy a new ship until you have enough money to buy all the modules needed for the task in hand at the same time. Any ship with mainly E-class modules is an absolute liability and will get you into trouble. If you carry anything on it, you'll get interdicted and won't be able to escape before getting blown up. Money is very easy to get from bounty farming (combat), mining platinum or Robigo sightseeing missions, so there's no reason not to have a suitable ship.
For any ship that you use for carrying stuff or running missions, the first things you need is A-rated thrusters and power distributor so that you can escape from any interdictions. The other modules need to be lightweight (D-class) for the best speed, while the power plant needs to give enough power for what you need - normally D-class is enough. Something like this:
A ship builder, outfitting and comparison tool for Elite Dangerous
coriolis.io
Drop a heatsink if you get interdicted. It'll keep you untargeted while you keep boosting away until the enemy can't do you any damage, while your FSD cools down until you can jump to safety.
You can get 9 million in 2 hours using a Sidewinder in a high resource extraction site to help the police kill the bad guys. Ask about that if you need to know how to do it without getting blown up yourself. it's dead easy and safe if you follow some simple rules.
