Lots of good advice above!
I'm the boss, and I give raises when I want. Which is regularly. I also make sure to pay enough to keep people from leaving.
However, I will side with the above posts in a slightly different way. Employees that get those "pieces of paper" are almost always the ones worth keeping, and remember, retention is accomplished by pay rate in any reasonable firm. It's not just the job performance, the personality and/or the hours worked, it's the dedication to the field, AND that is shown by qualifications.
Our flight department has 8 different aircraft. Imagine an airman (pilot or mechanic) who has just one qualification, and won't make the effort to become qualified on something else. We had that guy. His family was more important and quite simply, he absolutely would not pick up a book, sit in the cockpit and learn a new plane. Instead, he was heading home at 2:00 after his heli flight was done, to be with his wife and kids. Sorry, but that's not good enough and that is not what he was hired to do. He was hired to fly 2 different aircraft.
His inability to see what was needed, despite repeated attempts to coax him and directly tell him, resulted in hardship for his family as his source of income disappeared. He was a great helicopter pilot. His replacement was a great helicopter pilot and became a great Gulfstream pilot.
My qualifications on paper:
G650ER
G550
GV
GIV
GIII
727
PC-12
S-10
EC-135
MD 520N
MD 600N