A good way to make money and earn a good farm reputation is to do the part-time jobs that are offered by the Farmer's Union. The more jobs you do, the more difficult the jobs become. At some point in time you'll start to be asked for jobs which require you to gather large amounts of produce and fish. A lot of these jobs are easier to do once you have had your Storage Bin converted into a Fridge by Lucus.

One of the jobs that you might come across is to ship the King of Lake, the fish you need to give to Cozy in order to get a Power Berry. If you ship the King, doesn't that mean you can't get the berry? Not necessarily, as discovered by RPG ULTRA MASTER at the GameFaqs Harvest Moon 3 message board.

Step 1 - Get the King of Lake part-time job from the Farmer's Union.

Can't do this cheat without first getting the job! Go to the Farmer's Union and talk to the lady in the lower right corner. Tell her that you want a job and she'll give you one. If it's not the King of Lake job, select "No" and when she asks if you want a job again select "Yes". Eventually you'll come across the King of Lake job, which must be completed within 120 days and has a base-pay of 60,000G. Accept the job and head back to the Island.

Step 2 - Go to your farm house, call the Farmer's Union, and end the job.

Once you're back on the Island, head to your farm and call the Farmer's Union from your farm house. Select "P/T Job" to end your job. You'll be asked if you're "Done" with the job or you want to "Cancel" it. Select "Done" and you'll be told that you've completed the job!

You don't actually have the King of Lake, but the Farmer's Union doesn't seem to realize that fact! In return for finishing the job you'll receive 72000G when the Farmer's Union pays you at 6pm. You can even go back to the Farmer's Union and get the King of Lake job again that same day!