Welcome to Eve! Hope you are enjoying things out there. 
I’d personally recommend to first getting familiar with things more first. Run career missions and try a little bit of everything. There’s so much you can do in the game. It’s hard to really say what’s the best since to make ISK because, in my opinion, every playstyle can earn decent amounts of ISK.
It’s going to be slow at first when you’re just starting out; but as you gain skills and experience over time it will get better. For instance industry skills that boost your mining yield (like the Mining and Astrogeology skills that each give a 5% boost to yield per level; not including the ship bonuses for training the ships skill and fleet boosts).
For something quicker you can try market trading (utilizing tools like Eve-Central and Eve-MarketData to find items that you can bring to trade hubs to sell for profit). If you don’t have ISK on hand you can also try exploration which a lot of people (including myself) have had a lot of good luck in finding good loot that you can sell.
If you need guidance on how to do things; there’s a lot of great videos on the Eve Flight Academy YouTube playlist, there’s also a lot of other great resources that you can check out too.
Hope this helps you!