Things that can help.
- Better insulating the firebox. This can be adding fire brick to the bottom and sides or a insulated welder's cloth.
- The more ability to finely tune air flow the better. Put in a small smoldering stick of wood in the fire box and watch how the smoke flows through the pit. Play with the flew and the air intake until you understand how they impact the smoker. Adding more controllable air at the intake doesn't hurt. Not having a smoke stack sized big enough and in the right location to draw only allows so many options.
Here's my take. Pellet and wood chunk smokers exist for mainly for 2 big reasons as well as some others (ease and cost of acquiring and storing pellets, space saving, etc.).
1) Time. It's a commitment to tend a real offset smoker for 6 to 14 hours and a large number of successful smokes to have learn how each pit in particular works / doesn't work in general. Before trying to cook meat, do a long burn in experiment with different sizes (length and thickness) of wood and quantities of each added at a time. You'll quickly see how much and what intervals gives a fairly stable temp control.
2) There is some art form in cooking and smoking is no exception. It takes a balance of understanding the concepts and applications as well as understanding the specific smoker. And a cook that has put in the time to learn the ends and outs of managing a fire, the smoker, and a successful cook for each type of cut of meat.
Pellet smokers make it set and forget (temp control and no reliance on tending) and have removed a decent portion of the skill needed to get a good result. Still up to the cook for meat selection, trimming, seasoning, timing, resting, etc.
An offset smoker isn't for everyone. I've met my match in pits I just couldn't cook on. They were generally someone else's and set up in a way I didn't prefer. I use a pellet smoker when my schedule doesn't allow for the offset.
As far as losing control of the temp. My biggest suggestion is to thoroughly clean, burn in, and season before trying to cook anything else. Once you do, start the fire before worrying about the meat. Whether that is charcoal base with wood on top or a torch and just wood. Pits are a lot of cold metal, moisture, and grease. Getting it up to temp (and holding) before putting on cold meat gives you a head start on controlling the temp. Once you do add the meat avoid the temptation to add more than a small stick of wood when the temp inevitably drops because of opening it and adding cold meat absorbing heat. Not doing the above is #1 way for temp to get away from you.