When I first started on the BGE, I had some problems as well. I use half a chimney of lump to get started. Once good, I dump it in the midlle and leave the lid up. I also leave the bottom vent fully open. When it looks like the lump is good, I close the lid and leave the top vent wide open and watch my thermo. After awhile, start to close things down. The biggest thing to remember with the BGE, very easy to increase temps but once the ceramic gets high temps, it takes much longer to bring it back down.
You'll get a feel and get it dialed in with trial and error. You just need to get a feel.
Also, I'm at altitude in Colorado. Plus, we get all kinds of weather. Based on our wind patterns and where my BGE sits, it can make things pretty tough sometimes. In short, I got a Guru last year and it is Awesome. Winter, summer, rain, heat, etc. it does the job and was worth every penny for me.
BGE came up with the Eggcelerator for altitude guys like me but it's not even close to a Guru which does much more and is programable.
Pepperhead, Large BGE, Masterbuilt 7 in 1, Charmglow Gasser