Knowing how to give an awesome back rub is a skill that everyone should have! Here are some of the biggest mistakes to avoid, and some tips to do it right! Talk to Your Partner: Ask them where they have pain or tension. In your back rub, make sure to focus on those spots in particular.
Set the mood: Choose a quiet room, light a candle, play some relaxing music and get comfortable. If your partner prefers to be seated, put a pillow in their lap for support.
Go slow! Usually people move their hands WAY too quickly! Going slow allows your partner to adjust to the depth of pressure and allows you to actually feel what may be going on in terms of adhesions, or "knots". Also a very fast paced massage is likely more stressful than relaxing.
Use kneading strokes on the shoulders and neck, and apply a moderate amount of pressure on areas that feel stiff or hard, avoiding the spine and any bones. When you are applying pressure, try to really feel what's going on underneath your fingers, rather than just doing the action of the movement. It's like the difference between looking at a page of text and actually reading the words. Listen to your partner's muscles, and watch for signs of tension or relaxation. Adjust as needed.
Ask for Feedback: Say "how's my pressure?" and really listen to your partner and try to adjust accordingly. If you need to apply more pressure, try stepping back a couple steps and leaning into your movement instead of muscling it with your arms. For a lot of pressure, you can carefully place an elbow, forearm or closed fist and proceed very slowly. This is especially nice on areas between the spine and scapula (shoulder blade).
Take Your Time on each area and work methodically so as to not miss anything. Try starting with the shoulders, working down the back slowly, applying pressure to the middle and lower back, and finish with the neck and scalp. I like to leave the neck and head for last, because these areas are sensitive and will be easier to work on if the rest of the body is feeling relaxed.
Advanced Tip: If you really want your massage to be awesome, Learn some Anatomy! You can do it online at Get Body Smart, or try the Anatomy Coloring Book, or Trail Guide to the Body. This way when you're working, you can follow along the length of muscles.