I found this tip on the internet a while ago and I think it is good if you are clumsy (like me :))
Before doing your nails apply some moisturizer. This way you won’t have to deal with nail polish on your fingers.
With a piece of cloth/tissue/something, you can clean your nails before your base coat. Make sure your sides of your nails(lateral nail fold) are still covered in moisturizer/oil/what you used.
After you finished use a cotton swab if there are any mistakes :).
*Click on photos for source