Hint: More money
Go to a livery stable and buy four to five oxen. Then, go to trade and find someone who will trade money for your oxen. Trade the oxen for as much money as possible, but more than what you paid for them. Keep in mind that oxen differ in price depending on what location you are in. Keep trading the oxen for more money until the desired amount of money is received.

Hint: Catch fish
To catch fish, rest by a river, stream, or lake.

Hint: Pastor
If you are a trail guide, be a pastor. It will keep your morale high and you can trade sets of clothing at $10 profit apiece.