As I am currently trying to grow my nails, this 'how to' is more for stregthening nails, but this handy dandy tip also helps in aid of a broken nail.
What you'll need is:
An empty tea bag
Your favourite strong top/base coat nail varnish
A nail file
Maybe some tweezers, but this is optional!
The obvious bit here is to make sure your tea bag is totally empty! We don't want bits of tea leave left on the nail, not a good look.
Then you need to cut strips of the tea bag as to cover the tip of your nail, don't worry if they are big, we can sort that problem out later!
Now firstly, apply a nice even layer of your favourite base/top coat to your nail
Next, press your tea bag strip to the tip of your nail and make sure it all sticks to the polish (this is the bit you may want tweezers)
Allow that layer to dry and ensure the tea bag is stuck on nicely!
You probably still have the hanging edges of the tea bag right? Well nows the time to sort it.
Ensure that your polish is dry and the tea bag is stuck firmly, then all you need to do is drag your nail file over the hanging edges of the tea bag and they will file right off :) magically even edges!
Once you have done this and are happy with the edges, you can now apply a second coat of your base/top coat onto the nail over the tea bag to seal it into place!
I know right now it doesn't look like a very even surface tot he nails, but if you wish to paint over the top, you can use a ridge filling base coat (sold by many different places, I recommend Sally Hanson or Essie) and then proceed with normal painting!
Happy nails everyone :D if I ever find a specifically good brand of tea bag to use, I shall let you know!