First you need a good draft, .06 or better.Crack open the ash door when you start it with coal for the first 1/2 hour or so.
I drilled a second air hole in my ash door 2 1/2" so I could run mine a little harder.
There are 2 air holes in the front cast iron piece that need to be closed off with a piece of steel or something like that.Those holes let air in over the fire and you want ALL air to go through the fire.
Also fill it with coal.They dont't burn well with 1/2 a load of coal.
That should get you started.
I've been using a Hotblast for 5 or 6 years now and It takes a little patience but they do work well when you get the hang of it.
I also replaced the thermister(fan switch) with a normal fan switch from my plumbing supply.