I personally love a good poached egg but know people often find it hard to get these right. I think the biggest problem is the white not holding together and believe this is to do with the egg hitting the bottom of the pan before being cooked enough to hold its form. I've come across 3 methods to combat this:
1. The Swirl
The first method is to bring a pan of water to the boil. Once boiling take a spoon and swirl the water. Be careful not to burn yourself. With the water still spinning crack the egg in. The spinning motion should hold the egg white together in the centre of the pan.
2. Deep Pan
Bring a deep pan of water to the boil. Don't worry about spinning it, just drop the egg in. The motion of the egg dropping into the pan should cause the white to close round the egg yolk before it hits the bottom. The deeper the pan, the better.
3. Shallow Pan
Using a frying pan, for example, bring a couple of centimetres of water to the boil. Gently crack the egg into the pan and in a similar way to how you might cook a fried egg, spoon the boiling water over the white and yolk.
I've also found that adding a drop of vinegar to the water seems to help too.
Hope that helps.