How do I earn credits?
I want to earn more credits so I can purchase some of the more expensive player houses.
Which sources of credit income are available to me?
Other than races I'm unsure of the different ways to gain them.
Besides races, there are a few ways to get credits.
Finish certain Horizon Stories called "Businesses." These are World's Fastest Rentals, Upgrade Heroes, The Car Files, and I believe Isha’s Taxis. You have to be a particular level to open those but it's a good idea to get as many stars as possible in each, as you'll get cash every day.
If you have the Fortune Island expansion, you can get 10 million credits by going through it and doing the treasure hunts.
If you win Forza Edition cars from wheelspins or weekly challenges, you can sell them on the auction house for a good amount of money.
Wheelspin-exclusive cars are also worth a lot of money. Check if you have any of the cars on this list that you're willing to part with.
You can also set up very long races using the route creator or just creating a circuit race with a large number of laps. The longer a race is, the more credits you get when you finish. I believe it's based on the length of the course so doing it over a very straight road might be the best way to go.
Some cars have Car Mastery perks that give you credits, so check out the cars you have and see if you can buy any.