How should I properly route a mountain bike chain to ensure smooth operation and longevity?

To properly route a mountain bike chain for smooth operation and longevity, make sure the chain is the correct length and properly lubricated. Ensure the chain runs straight through the front and rear derailleurs without any kinks or twists. Check for any signs of wear or damage on the chainrings and cassette, and replace them if necessary. Lastly, regularly clean and maintain the chain to prevent dirt and grime buildup.