I find that the problem is not as much the simple wind speed. Sometimes flying in 10mph winds is no problem. 5 mph winds may be a big problem on certain days and in certain locations.
The larger problem is air turbulence. Turbulent 5mph is much more difficult to fly in than 10 mph smooth air. Yes, normally there is higher turbulence with higher wind speeds, but this is not always true.
Turbulence is unpredictable and that's where the flying problems come in. A beginner pilot has to think too much and hasn't developed instantaneous motor reflexes that are essential in turbulence.
Practice by flying in bumpy 5 mph wind that is more an annoyance than a life threatening crisis.You'll need to keep your airspeed higher than normal, especially during landing and takeoff, as a sudden puff from behind can stall an airplane, which then falls into the ground with great vigor. It feels like you're literally sucked into the earth.
Finally, severe turbulence is best just avoided. Unfortunately, it is traditionally discovered after take-off and before the inevitable landing.