Name all your bones descriptively.

Name bones that will be mirrored like “Arm.L” “Arm.R” etc. When mirrored the names will switch (if you use flip names)

In the bone properties section, you can set bones to *not* inherit rotation and position. Useful for hips.

Select multiple bones, then press Ctrl+P. The *last* selected bone becomes the parent. Choose “keep offset” to keep them in relative positions to parent.

With bones, you want to use “bone constraints”, not normal constraints

Use the gimbal selector at bottom, choose “rotate around normal”

To connect mesh to armature, select mesh, then armature, then press Ctrl+P and choose “automatic weights”

Use Bone Constraints → IK Constraint to make bones up-the-chain follow that bone.

Use Bone Constraints → Xpos and YPos to make bones stick to another bone

When mirroring bones to the other side, turn on X-axis mirror on the left menu. After mirroring, while still selected, use the Armature menu at the bottom and got to Armature → Flip names

Make sure to know the difference between pose mode and edit mode. You can copy a pose from the right over to the left in pose mode

To add IK, go to pose mode, and add bone constraints (Tracking → Inverse Kinematics)