After shaving your armpits your skin may not be left in the best condition. While they may not be on show all the time, you'll feel much better if you keep them smooth and fresh.
Shaving can lead to all sorts of problems, including ingrown hairs and rashes. Before getting your razor out, exfoliate the area as this will help prevent hairs from curling under the skin. It will also get rid of any dry skin on the surface; anything that prevents the blades from gliding smoothly can cause razor burn afterwards so it's important you start with a smooth surface.
Using shaving foam or oil is a must to stop any cuts or irritation - choose whatever works best for you in this case, as long as it goes on easily and allows the razor to move.
The direction you shave in plays a part in the finished results; it's more than likely you shave against the growth of your hair, but by doing it in an X shape it will give a closer shave with no stubble left. The hairs actually grow in a swirl pattern and going in one direction won't catch them all.
Once you're hair free, the task at hand is keeping your armpits in a good state. Hydrating is part of this process as the last thing you want is to have dry underarms, especially as the skin is so thin. Every time you're in the shower have a good exfoliate to keep those ingrown hairs at bay, followed by a lashing of moisturiser or body oil.
Deodorant can dry your pits out, therefore you may want to opt for a moisturising option if you haven't got the time to moisturise.
Another side effect of shaving is the skin under your arms darkening, which is caused by reoccurring friction in the same spot. The same can happen for your bikini line, but there is a way to tackle this problem. There are some ingredients in skincare which have brightening properties, such as kojic acid, which is used to treat acne and dark spots. Applying these once or twice a week (use sparingly) will brighten your armpits over time.
If problems continue to arise despite following these tips, see a doctor for advice on where to go next.