Missioning income doesn’t just come from the ISK rewards you get from the agents. The corporation you run missions for will steadily pay you with Loyalty Points. Through the in-game Wallet -> Loyalty Points, you can click the corp you run for and find out where their nearest Loyalty Store is. You can then check https://www.fuzzwork.co.uk/lpstore/ to see which items would be best to sell on the market or directly to other players. Watch out for daily volumes – you might not want to buy 100 of an item that only sells 2 per day!

Want to know more about Loyalty Points? The UniWiki provides!