Joint areas like elbows, knees and hands are some of the hardest to tan. There is more skin in these areas which can cause them to come out darker and the amount of friction they experience can also make it tricky to keep the tan even. Below are a few options you can try out and see what works best for you and your skin type!
Using a tiny amount of body lotion on your knees and elbows prior to applying self tanning mousse will create a barrier that will prevent the area from over-absorbing the tanner.
Dry Mitt Method
This is my personal favorite and super easy. Apply tanner limb-by-limb but skip the joint area. Once you have finished the limb, go back with a "dry" mitt (no added product) to take care of the joint. There will be just enough residue to tan the area without overdoing it.
This is a great tool for blending! Applying tanner directly onto the brush and do so sparingly- a little will go a long way here. Start in the center of the areas and rub in circular motions feathering outwards. Don't be afraid of overlapping with your previous tanner, this will create a seamless look.