When I started mining I did a bunch of trial and error and I learned a lot doing this. I have tired a few different approaches suggested on this forum. In my experience I have found it is best to mine the must valuable coin that you think is the best one. If the hardware you have is not up to this than mine the most valuable coin your hardware supports and convert it over to the above coin. Now if you want to speculate on something new or that you don't own buy some using your exchange balance. My two favorite coins are Bitcoin and Etherum. The speculative coins I have bought and mined are ripple, zec, and btg. I continue to mine Etherum. I have not had any reason to cash anything out. My future plan is to wait for the value to peak and then sell enough to at least recoup my initial investment and maybe take some profit to buy something nice. I will leave the rest for a rainy day.