One of the best ways to get money is to hunt in Tall Trees. Once there try and find:

Bears.

Beavers.

Elks.

Foxes.

Eagles.

Although these pelts/fur might not cost much, however they seem to be worth more in Mexico. That being as you don't see bears, or beavers there.

You could get alot of money, by also hunting for birds.

Hawkes

Owls

Songbirds

Ducks

Will be worth quite alot of money. However you need alot of feathers to get more then 500.

I hope this helped in some way.

If you have any more questions, leave it in the comments. And please feature this so people can, in some way be helped if they're struggling/want to know more about the game.