They all got you pretty well covered here, esp. Wampus - I just want to emphasize keeping the exhaust 100 percent open all the time - things got a lot better for me when I started doing that.
I found BBQ Nirvana when I started burning sticks in my Spicewine thanks to the advice from Phil. It's about as good as it gets. But even in a different cooker I still apply the same theories as posted here. A small hot fire is the way to go regardless of what you're cooking with. Good luck with the Lang!
On my Lang 60 I use 1 chimmney of K to get a bed of coals then put 3 sticks/logs on the fire with the 4 intakes all open. As others have said leave the exhaust vent all open. When the temp is about 300 I shut the vents to open just a sliver. I add about 1 log every 40 minutes to an hour depending on the outside temp. If it is windy my cooker seems to work best with the firebox facing the wind - a strong cross wind and it is hard to keep the temp up.
If you have a hard time finding wood I would recommend making a charcoal basket and burning mostly charcoal or lump - I know others that have done this and actually get a long burn time using this method...and obviously use a lot less wood.