Going in through the belly butten or armpits does the least damage as far as scarring goes, the belly butten entry is almost invisable. As for how to have them look natural, that all depends on the doctor doing them and how good he is, and also about what size you choose and if its even proportionate to your body. Most women over-do it and fill them too much and thats what causes the "fake" look.
Well I am getting these for my wife's birthday next year, and she said she would like a full C. I do not have a clue what a full C is, she is right now I believe a B or C, I have also heard the arm pit or belly button is best. I have also been told you want the implant under the muscle.