On capturing likeness

I guess i could safely say, i cannot capture a likeness.  Ok so this oil painting is totally unfinished, but surely by now i should be picking up some of their characteristics?  No?  These little ones are 5 and 3....i've made them look about 50!  I am thinking i need some fine art lessons.  Or actually sit down and draw like i used to draw.  These days i'm like a bull in a china shop!  I guess thats because there is so little time these days.

 What are your techniques for capturing the look or spirit of someone on paper?  Ideas please :)