Watch the Guitar Lab: Precision Strumming online guitar lesson by Brad Carlton from Guitar Lab: Precision Strumming

Hi, Brad Carlton here, and welcome to Guitar Lab: Precision Strumming. This course will examine the nuances of picking and strumming with an emphasis on rhythmic confidence and control of voices and dynamics. You'll learn how to scrutinize your technique and develop exercises which will increase your inventory of picking and strumming patterns.

Some of the topics covered are: free strokes, rest strokes, picking options, bass and treble targets, "hill or valley" picking, ghost strokes, the "choke", palm slap, ring vs. dead, sustaining open strings, and eliminating squeaks. The information in this course will benefit both the beginner as well as the seasoned guitarist.
Here's something for your consideration while going through this course. Accuracy: How close you can get to the correct result. Precision: How consistent you can get that result.

Accuracy refers to the closeness of a measured value to a standard or known value. For example, if in a lab you obtain a weight measurement of 3.2 kg for a given substance, but the actual or known weight is 10 kg, then your measurement is not accurate. In this case, your measurement is not close to the known value.

Precision refers to the closeness of two or more measurements to each other. Using the example above, if you weigh a given substance five times, and get 3.2 kg each time, then your measurement is very precise. Precision is independent of accuracy. You can be very precise but inaccurate, and you can also be accurate but imprecise. For example, if on average, your measurements for something are close to the known value, but the measurements are far from each other, then you have accuracy without precision.