Other than the fees and the APY, it really depends on the future value both assets and harvests. To Farm, not farm, or just buy the harvest.
1. When To Sell Your Asset
When asset will go down and harvest will go down, sell everything unless the annual percentage yield (APY) can cover for the loss.
2. When Not to Farm but Buy Harvest
When asset will go down and harvest will go up, forget about farming and just buy the harvest. If you farm, you will get less and less harvest as the asset goes down.
3. Farm or Buy Harvest Depends on Fees and APYs
When asset will stay still and harvest will go up depends on the fees and APYs. If farming costs low fee and produces high yield then farm, otherwise just buy the harvest as you may not get much harvest and/or you need to pay the fee.
4. When Farming With Highest Yield Strategy
When asset will go up and harvest does not follow whether it will go down, stay still, or does not go up much, then farm using the strategy with the highest yield. If you do not understand what yield is, it is to use the harvest to farm for another harvest either by farming another different type of harvest, sell the harvest to asset to farm more harvest again, or some complicated combination where Harvest Finance provides that strategy for you.