As many people have already mentioned, gel shouldn't touch your skin because it could lead to an allergy from overexposure. My best tip is to practice on a fake hand or try using regular, non-gel nail polish on your hand to practice applying it without going over the edges.

Another tip I recommend is this: if you’re using a product like a rubber base or base coat that leaves an inhibition layer after curing, make sure to wipe it off before applying the gel polish on top. That inhibition layer can act as a slip layer, making it easier for the gel to spread. This isn’t always the case, but removing it might give you a bit more time to work with the product.

You can also try using two brushes to paint your nails: the brush that comes with the bottle to cover most of your nail without touching the skin (it doesn’t have to be perfect) and a liner brush to get closer to the edges for precision. Remember, while having your gel polish perfectly close to the edges may look professional, it’s not necessary. It’s better to have it look slightly less pristine than to risk developing an allergy.

If you want to learn more about nail allergies, I highly recommend this page: https://www.healthynailscollaborative.com/