Welcome to the forum Grahm and congratulations on the new smoker. The
WSM is one of the best. I had an 18.5
WSM and still have my 14.5
WSM.
I would start with getting the 'Menion Method' down first. Try one full
chimney starter of unlit charcoal in the charcoal ring and then one third to one half of lit charcoal on top of the unlit coals. Lots of good instructions out there, Google is your friend.
As far as mods go I don't think the
WSM needs much. One thing that will really help is to get a second charcoal grate and place it cross way to the original grate and wire them to the charcoal ring. This creates a handy basket to separate ash from un-burnt briquettes. Next, find a stainless pizza pan on
Amazon to fit in place of the water bowl for high heat, fast cooks. Be sure to foil your water bowl, inside and out, whenever you use it. Makes clean up much easier. Get to know your cooker before going crazy with modifications. Learning fire management is more important. Like I said, the WSM doesn't need much. Weber certainly got it right with that cooking machine.
One more thing I might add. You don't need meat on the grill to fire it up and play around with temperature control. Just burn some charcoal and have fun.
Once again, welcome and congratulations.