What should you do with mined coins—hold or sell immediately?

The practical approach
If mining costs exceed earnings in any month, sell immediately to cover expenses—otherwise you're funding the operation from savings. Sell at least enough to break even. Beyond that, personal risk tolerance determines strategy.
Avoid holding for a "moon shot"
Many miners hold coins expecting dramatic price increases. History shows some coins do rise, but many crash or disappear. Holding concentrated positions in a single coin is high-risk. If you can't afford to lose the coins, don't hold them gambling for gains.
A balanced middle ground
Consider selling 50–70% immediately and holding the remainder if you can afford it. This covers costs and captures some upside without risking the operation. Use limit orders on exchanges to sell at specific prices rather than market orders that trigger high fees.
Tax implications
In most jurisdictions, mining earnings are taxable income at the time you receive them, and selling at a different price creates capital gains tax. Keep records of when you received coins and when you sold them. Consult a tax advisor—tax treatment varies significantly by location.