I manual focused because it was a 50mm Nikkor-S that is about thirty years old :-) The second shot was with AF (20/2.8 AFD).

The first picture isn't really sharp (and the subject was speaking so his chin is more blurred then the rest), but acceptable in small sizes, while the second picture can be blown up at decent sizes !

On the D200, matrix metering is quite good for most cases (apart when you have a direct light in the frame), because I started shooting a long time ago I'm more familiar with centered average metering, as I know what I will get.
I usually keep spot metering for peculiar cases, as in the second picture with the big white diffusing background...

Don't worry about improving one aspect at a time, it'll soak in :-)
Apart from very specific shoots (macro, astronomy, stills, etc.) you shouldn't have to "think" too much, meaning the basics (composition, settings, etc.) should be more on the instinctive side... But to get there, most of us ruined kilometres of good film :-)

"What can I do, What can I write, Against the fall of Night". A.E. Housman