The art, (and it truly is!) of being able to sing while playing can be a real challenge for many people. There are certain instruments, or more accurately, styles of playing, that are more condusive to being able to properly accompany singing. Usually, if you’re a lead guitarist, as I am, you have to be able to bring your part down to a more minimalistic approach if you expect to be able to keep playing while singing. You can see the many approaches by different musicians and how they have it worked out. For example, the great Levon Helm, who I did an album with 3 years ago, is simply amazing in how he sings while playing drums! It’s true that it’s a “rhythm” instrument, which usually makes it easier to sing with, but he manages to play through the fills, and all the complex parts he likes to play! Paul McCartney represents perhaps the quintessential “singing while playing” example, as he is someone who went from being a guitarist/singer to a bassist/singer in the biggest band of all time, and who became one of the greatest singers as well as bass players ever! This is especially impressive in how he is so adept at playing melodic bass lines, while singing melodies that are seemingly totally unrelated!
The other extreme is represented by the great B.B. King, who literally slings the guitar aside as he sings, which also adds to the dramatic effect of his vocals, and then only concentrates on his lead solos as well as fills. It’s a very dramatic effect, and it’s become literally a “signature” approach of his that he has developed to a fine art form!
I have always approached it by simplifying my playing during my singing, or having a little fun by singing harmonies to my guitar lines, or doing some unison with it. As long as you “lock in” with your rhythmic approach on the instrument, it should work out fine! The Chuck Berry approach is probably the most classic Rock n’ Roll style, where he sings over his shuffle licks, and then plays his rapid-fire fills in between the vocal lines. When it’s time to launch into one of his signature solos, he them plays in a style that has already been established and imprinted by his singing and playing of “fills.”
So try the various approaches, and there are many….you’ll know when you reach that comfort level in regards to playing and singing at the same time, and of course, when you have other players to rely on, you can also work on being able to leave some space, and to truly be the “lead” singer, as well as the “lead” guitarist! Best of luck!