I've been burning reading anthracite nut coal in my new Harman insert since November of this year.
The salesman told me I'd curse the thing for at least a month until I got the hang of it. Burning coal is nothing like burning wood, and it takes time to get to know your stove's tempermant.
I've finnally gotten to the point that I can keep a good fire going day after day, and have hit my stride.
My only advice ( as a coal newbie ) is to keep the fire "strong". If it's not "strong", handle it gently and give it what it wants until it is "strong" ( air, air, air ). Once it's "strong", you can do just about anything to it.
The challenge is to discover your own stoves definition of "strong"