For the photolab ask them what color profile they use and then save your image with with those settings. For example adobe rgb or srgb whatever. Calibrate your moniter (should be doing this anyway if you are a working pro). Then order a few small test prints and check if they match. If not you could adjust the image to match. For example - print is colder in tone than your screen then just change your white balance. (Its always bloody white balance!).
Also add extra sharpness in post for print.
For picky customers just explain that you're a photographer and those kinda things are not what you do. (You record the scene as it is).
Photoshop is good though for portrait retouching. I would learn that aspect as you might need to remove a zit or two and get rid of bags under eye.
Good advice... also a good idea to only retouch 'temporary' blemishes on portraits unless the client agrees / requests. You may think straightening someones wonky teeth is a must do but the owner might be proud of them and take offence!