Jason Waters
Lastly,

Buy premium thinset with latex (I think it's latex, can't remember) modifier which increases the bond. Last time I did floors, they cheap grey stuff was like $4 per bag, the white premium (which I used, but you don't have to pay for white, unless you need it dues to light color grout like me) was like $18 per bag. I imagine premium grey is in between. Sometimes you can buy a liquid modifier you add too. Applying it right helps a lot too in getting a good bond. You just have to do it a while to get used to what needs to be done.

The others have covered the prep.

I wouldn't tile my shop, but that's me, and a personal decision. But I do wish I had painted mine when I moved in........

I have many runners of anti-fatigue mats on my concrete floor.

Jason