Trouble painting weights

I dont know what it is but the rig is okay but when i bind it to the mesh and start to move around the body part, the legs are fine they move nice but its the shoulder area where it deforms quite bad lol. I know the problem and how to resolve it, it rest all apon the weighting that we apply to the mesh. I had a go at it isolved some areas but couldnt do the same for others. If you want next time im in, you guys can have a go at painting weights if you want