Hey Jim,
Make sure you have settled on the string brand and gauge that you think you'll end up with. Play for a while, let em settle in as well as you going through your regular playing routine of songs, styles, the things you do on your guitar. Make mental notes of how the action feels
in conjunction with how the guitar sounds when you're strumming vs picking vs using fingers (or whatever your personal varying styles are) over different songs, and do the same for those songs up the neck. This "evaluation" wll give you an idea of where your guitar's action is vs where you may want it to go. If it plays great now, you don't really know that it can't play better after a set up; and yes, it can get worse (meaning it's set up not to
your personal liking).
A "good setup" means that the action overall is tailored to the player's style. So
you set the standard here. I also recommend to anyone owning an acoustic that you get a ruler that measures in 64ths of an inch. These little metal rulers can be had at your local DIY store for a couple o bucks. It is best to be able to measure what
exactly your string height is at the 12th fret, low and high E. You should know what it is now, before you get it done by the tech, and then measure it after it's been worked on. The string height at the 12th and the neck relief has
everything to do with your comfort with the guitar and the tones (or buzzes) it produces. Going by "feel" or memory here is a bad idea as you want actual measurements so you can truly know and compare with
objective certainty what going up or down 1/64ths or changing neck relief actually feels and sounds like. IMHO, it's worth taking a bit of time and analyzing the whole setup process, understanding its effects on tone and play, before you actually start getting things done. Oh, BTW, the tech doing the work should have a good reputation ...setting up a guitar, in truth, is pretty easy; but done by someone who is either incompetant or disinterested can yield very poor results. Hope that gives you a few things to think about

Edward