No bouquet to give

"I said, 'Wait a minute, Chester, You know I'm a peaceful man...'" Robbie Robertson

1. Convert to Lab colour, and add 10-20% saturation. Lab colour saturation is more subtle and natural-looking than RGB saturation, and less sensitive to noise.

2. Duplicate and add an overlay blend layer at between 25-50% opacity. This brightens up the colours in anything and adds some contrast.

With a digital camera like the D80, the ratio of the CCD is about 1.5 compared to 24x36 (or 135 format). That means that when set at 50mm focal (for example), the 135 equivalent (or apparent) focal length would be 75mm.

The old trick of trade, stating that you have to set your speed at least at the focal length value (1/50th or 1/60th for a 50mm lens) seems to apply with the so-called crop factor (1.5). That's for camera motion blur vs the subject motion blur !

At the tele end of your zoom (105mm) you should be at a speed of 1/200th (1/157th)if hand holding or use a tripod for slower speeds.

I'm sure that, looking at the exifs, you'll find you have a higher rate of sharp pictures at the wide end then at the tele one... :-)

Then you have the aperture (or f stop). Setting it wide open (small number) allows for more light or a lower speed value in a given light... But it reduces you depth of field (or DoF), meaning that the plane of sharpness is quite shallow ! Add that problem to an auto-focus or manual focus a bit too near or too far and you get a seemingly not so sharp picture !

Of course, all that is above is for a given ISO value (the good old film ISO/ASA number). But with the D80 you can add ISO as another variable by changing it or allowing it to change automatically with auto-ISO.

You can try a "false" manual setting... You get in auto-iso mode, in manual mode, you set a speed value, fixed high enough for your lens crop factor. You then forget about it and use your camera as in mode A (aperture priority), setting the f stop in relationship to DoF.... Then take the pictures !
Auto-Iso will adjust ISO value accordingly, setting it higher if the scene is darker or lower if the scene is lighter...
It has some limitations though. The higher you go with ISO, the more you are prone to "noise" (or digital grain), and you can't go much lower then 100 ISO (if it hits the floor, you'll have to act on speed or f stop)!

Does this helps ? :-)

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

I have that issue with my 50mm since I tend to use it for low light shots and have the aperture on f/1.4.

I find that with the 50mm, even though it feels in camera that I have focussed on some specific part of the frame, the shot turns out with it focussing on the wall behind or slightly to the side of the person or subject of the shot. Most annoying.  

Here's a good tip on aperture and DOF

Ad astra per aspera

here is my first (very amateur) entry, from one of two visits last week to the Hangzhou Botanical Gardens.

Truth unfolds in time through a communal process.

The problem I see here is more about including the light appliance. It adds a "hot spot" on DSLRs cameras that are not so good on extreme values (as can be seen here with the posterisation effect) !
No, the real drawback of such a framing with the light appliance is that it fools your metering system (matrix, average, spot ?) by trying to find a mean value between the very dark shirt (dress?) and the very white hot spot !
As it can't, you loose all details in the shadows AND in the hot spot...

Framing without the appliance would have given at f/1.4  and with a "normal" speed an ISO value that would have kept the shadows correctly illuminated and less noise even at a higher ISO...!

Then there is the focus problem with the shallow DoF (what settings for AF do you use ?) that might have been corrected by manual focus... :-)

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

The lighting is horrible - mixed tungsten and flourescent as far as I can tell - I can't colour correct is properly.

Why didn't you use a bit of flash? It's a pretty formal portrait.