hey everyone, I've just recently started getting into portrait photography instead of urban/nature. I have 2 sb600's and I'm looking to get an umbrella. I'm thinking of something around 41"s. I want to start with one and see if I can utilize 1 before getting another. I'm not sure if I should get a white or silver surface or maybe a white surface that can also be a shoot-thru. Also, is a sb600 strong enough or do I need a stronger speedlight?