How NOT to mine Bitcoin 101:
1. waste time on internet shopping for miners
2. Make bad decision and buy miner on ebay, amazon, or worse from some manufacturer
3. Wait to receive miner while the value of your miner plummets and bitcoin difficulty raises exponentially every day
4. plug in miner and start mining coins at the rate of .00001 bitcoin per day
5. after 30 days add up the $3 you made and calculate how long it will take to pay off your overpriced miner
6. list miner on ebay so you can sell immediately as the price for your miner is now 25% of what you paid
7. begrudgingly pay ebay 10% of sales price
8. invest remaining money in buying bitcoin
9. repeat every six months
FTFY.
Learn how the blockchain adjusts difficulty and make your own spreadsheet to SWAG what the future holds. Over estimate and compare with
AVAILABLE miners (NO pre-orders). If you find a miner that meets your predictions, go for it. I've been able to find them despite the many others that are too expensive.
For me to try mining again this is what I would need:
1. Be able to mine at least 10 BTC a month initially, anything less and I just don't really care, I am not interested in watching paint dry.
2. An ROI of no more than 30 days. I just don't think I would trust any difficulty estimate that is more than that far away as so many insane miners are allegedly coming online every week.
3. Hardware I can buy today and express ship to my house so I can be mining in two days
4. Trusted hardware
I just don't think you can get all of the above right now but I stopped looking at hardware a month ago...