Experimenting
Over the weekend, I’ve tried to use the new nail polish I bought in dark red. First time I’ve tried any darker colour on my fingernails. While I love the colour, I’ve having trouble “staying between the boundaries”. 
Oddly enough I don’t have the same issue with toenails.
I’m going to google and see if I find anything useful.
I find that the best thing to do is to just paint your nails fully, ignoring any “wrong” bits.
Then, just dip a Q-tip into nail polish remover and gradually remove the wrong bits…it’s easier to ensure a perfect nail job that way.
That is what I’ve been reading too! Thanks for that, might try it later.