FAQ: Q: Shift+Ctrl+C is not bringing up the add constraints menu. A: This will only work if you're in POSE mode.
Q: Leg/arm is not bending (or is bending in the wrong direction) when I move the ik bone. A: In edit mode select the joint (where the upper and lower leg/arm meet) and move it slightly so that it has an initial bend in the direction you want.
Q: If I move the ik bone down to far the leg starts stretching at the foot. A: Parent the foot to the lower leg bone instead of the ik bone. To make the foot still follow the rotation of the ik bone, select foot bone in pose mode and turn of inherit rotation in bone properties. Then select the ik bone, shift select the foot bone and press shift+ctrl+c and add a copy rotation constraint. In the constraints tab set both of the 'Space' fields to Local Space.
Q: Arm or leg moves unpredictably/wildly with even the slightest movement of ik bone. A: IK is most probably still parented to the lower leg/arm bone. In edit mode, select the ik bone and press alt+p to clear the parenting.
Q: What is the period key? A: The full stop you (should) put at the end of a sentence.
Q: How do you flip the bones after duplicating with shift+d? A: Press 's' to scale, 'x' to constrain to x axis, and '-1' to flip. Left click to confirm.
Q: Whole rig moves wildly and unpredictable in pose mode. A: The chain length on one of the ik bones is 0.