I use Royal Oak Lump Charcoal. Lump charcoal burns hotter and longer. I use it to get the smoker up to temperature then go with a small piece(s) of hickory.
I highly recommend Jeff's 5 day e-Course if you haven't already been through it. And, again the modifications are a must IMHO (or the one's you believe necessary), and possibly another thermometer to check grate level temperature.