I find a wealthy hitech industrial station planet with high population and base out of it as the hub for trade routes. High tech is the top of the food chain so a high tech industrial wealthy with high population will typically have serveral high supply and demand items from which to build your trade network. Also, look for trade routes with items that give you 700+ credits profit.
I took my starter ship and stripped her down to add more cargo holds. Even took out the shields. The money I made from selling the basic modules gave me plenty to buy items and start trading. Work you way up to hauler and strip it too to add more cargo space. Then cobra etc. a trader cobra can have 60 tonnes of cargo and still be very fast! If you mess up and lose your starter ship just redo.
Never put more then 50% of your funds into any one load of cargo. Bad things can happen!
Only do missions that involve moving items as part of your trade route. Combat, smuggling, Unidentified signal sources all can lead to fines or worse. Avoid them.
Once you have mastered trading and have a bank balance you are comfortable with you can then go buy a second ship for combat and fit it very nicely.
When traveling from the star to a station, move above or below the planetary plane so that other traffic going to or from your destination is above or below you. You can only be interdicted fro directly behind your ship. If you are above or below the main traffic you will easily see someone trying to get behind you. If you see them trying immediately drop out of super cruise so they lose you. I count to thirty (don't know if this matters really) then re jump into super cruise to my destination.
When approching a station in super cruise I like to come in from the direction of the nearby planet or moon. This will drop me out facing the entrance. I go to full speed and boost then ask for permission to land. About 2k out I max my power to shields and drop landing gear. This will slow you down fairly quickly. Line up on entrance as you approach. If you cam in fro Planetside then alignment should be simple. Drop to a speed you are comfortable with to enter station.
I do the same for outposts but finding the pad can be a pain if it's not on the side facing you. On outposts, beware of structure as you land and take off. It can/will kill you if you are not alert. When leaving just go up enough to clear forward structure an move forward straight ahead. I typically boost directl out from the station. Once boost is finished I then line up my destination.
Lastly, if you get the too fast warning, set your speed to middle of blue band and dip about twenty degrees below the destination target. As soon as you pass it pull up to make a tight spiral back to the target. The gravity well that made you go too fast now rapidly slows you down as you spiral back onto your destination. Easiest and fastest way to handle this problem. Even faster then nursing your speed to prevent the acceleration as you just close on your destination too slow compared to the spiral method.
Fly safe! Make lots of money! Have fun!