I have been helping run a 25+ PC mine that owns some rigs of our own and hosts other rigs that we order and build for customers. Has been about 5 months going strong. Here are some points I tell people that want to start mining. This all applies to non-ASIC mining.
- Have a good group of people that mine who are willing to help you out with advice/question answering.
- Have a want to improve your knowledge of new coins, mining software, and techniques other enthusiast miners are using. There will be some days where you want to give up. You will probably put in hours changing settings in a computer and the issue will not be resolved. Some computers will simply not work sometimes. It is good to have spare parts sitting around so you can replace parts. I have replaced every single part of a computer to ensure I had no bad parts, and it still did not work. I ended up putting EthOS in the rig and it worked. Might have been a Windows installation issue. Still not 100% sure
- Cooling will be around 25% of your electricity costs. It is very important to keep the computers cool for the longevity of the computer's life. Sometimes the GPU fans will literally warp and will affect the Hashrate of the GPU because it is not getting the airflow it needs. The GPU will eventually completely die without proper cooling.
- Dust. Keep your space clean. Also important for the longevity of the GPU.
- Electricity cost in residential areas are ridiculous. Call your Electricity provider and see if they have a payment plan that is better than the one you currently have.
- Do you have enough circuits to support the amount of PCs you will use? When I started mining in my house, sometimes a blowdryer would trip the circuit breaker, or even multiple breakers. If your electricity lines are old they will be less efficient and get hot, resulting in both energy loss and fire hazard.
- Be sure to cash out when you feel like a genius for mining a certain coin. Unless you are already well off, cash out a little bit every now and then to cover your costs.
- Mining is loud and hot. People often don't understand how loud and hot it really is. Be sure your spouse is ok with it XD
That's about all I got now.
Be sure to keep up to date with new mining software and techniques people are using. For example, some coins will announce a fork in a week, and if you don't update your miner before the fork you won't be able to mine it.
Good luck! Let me know if you decide to use any of this advice