The most unique fundamental technique used by steel guitarists which isn't used by most other string players is blocking.
Blocking is the only way to keep unwanted strings from ringing together.
Blocking is absolutely necessary and must be learned before proceeding to more complicated maneuvers. Without blocking the strings would just ring out and mix with each other, causing an atonal and muddy sound. At times you may want the strings to ring out, but for now exercising control is what's important. You want to get to a point where you can either mute the strings or let them ring without any difficulty.
There are three blocking techniques.
1. Palm blocking
2. Knuckle blocking
3. Finger blocking
Palm blocking. To palm block, the pinky is kept in line with the palm, the wrist, and the arm. The strings are plucked then the palm and pinky, still straight, come down on the strings to mute them before the next string(s) are picked.
Knuckle blocking. Knuckle blocking is the same as palm blocking except you fold your pinky and ring finger under your hand and use the top of them to mute the strings.
Some steel guitarists prefer knuckle blocking to palm blocking. But they are not mutually exclusive - one should learn both. Knuckle blocking will be necessary if one wishes to let some strings ring out while others become muted. Knuckle blocking is also useful for controlled pitch harmonics. (These techniques will be addressed in later lessons).
Pick blocking. Pick blocking is using the finger picks or thumb picks to block the strings. The strings are picked and then immediately stopped by the same finger or, occasionally, by a different finger. This method is tricky at first, but offers many advantages for speed and accuaracy. This is the method I use most often to block.
Those are your 3 blocking techniques. Focus on getting these down with the exercises below. Don't get frustrated, just keep at it. Once you master blocking the rest of the instrument will be much easier to learn.
Now that we know how to block we can practice playing our notes with more precision. Here are the same exercises from the previous section on the right hand (exercises 1 and 2):
1. First play it ringing out like before with no blocking.
2. Then play it "staccato." That means to play the note and immediately block it leaving empty space between the notes. Try it with all three types of blocking.
3. Finally play the note and let it ring. Then, right before striking the next note, block the string. Try it with all three types of blocking.