I really like allover patterns on my nails, for instance (and especially) polka dots. It isn't hard when you use a dotting tool, it only takes some time. I always start with a dot in the middle of the nail, and then add the other dots around it. Here are a few pictures of polka dot nails I made in the past.
This was the first time I tried it, and it worked out suprisingly well. I adore these colours. I only really dislike the fact that I included my cuticles when painting my nails! Ulgh. I'm older and wiser now. (This was a few years ago.)
Dark purple with matte dots! I had to take a photo with flash, or you couldn't see the dots. Off topic: I think the shape and length of my nails are absolutely perfect on this picture!
And this is the most recent one, I made this on my cousin's nails a few days ago. It's an attempt to an artistic picture, haha.
The clue for nice polka dots: be patient and precise. Good luck!