This is a very good question, and one that is frequently asked. Fortunately, we have a community FAQ to answer it. 
First things first, though, you will not likely be able to use the same model switch for both smart bulbs and dumb bulbs. You will probably have one kind of switch for smart bulbs and one kind of switch for dumb bulbs.
The exception: switches that do double tap
There is one exception to this: if you get the kind of smart switch which has different tap patterns, like single tap, double tap, and triple tap, then you can use the single tap for dumb bulbs which are on the circuit branch controlled by that switch, and use the double tap and triple tap to control the smart bulbs.
Because the double tap works by having the switch send a message to the hub and then the hub sends a message to the bulbs, it does not control the current directly for those bulbs.
However, the use of double tap and triple tap type patterns tends to be very confusing for guests, and not everybody likes it. 
So that option is available, but not that many people use it. If you would like more information about the switches which offer different tap patterns, let us know.
Discussion of several different methods for combining switches and smart bulbs are in the community FAQ
For discussions of the best kind of switches to use with smart bulbs, see the community FAQ. There are a number of different methods described there with examples of specific device models. 
The topic title is a clickable link: