mikehit

A beauiful scene indeed and one worth capturing.

I see it was shot at ISO 125 - you should not have much noise at that setting. One thing you could try is turn the camera portrait mode, then shoot an overlapping sequence and stitch the images together: if you don't have a tripod, use a wider angle and crop to get the composition you want.
Two things emphasise noise: recovering an underexposed image (was it?) and oversharpening, and to me it does look oversharpened (look at the white border round the tree line and the mountain edges) - have you tried to compenate for camerashake? If so you should be able to get shoot at ISO 400 with little or no noise, and that would give you a good shutter speed as well. I see there are some dirt marks on the left hand side on level with the rooftop which could be cloned out.

Regards composition, it is potentially a very attractive shot but unfortunately there is not a lot to grab my attention. Having the building dead centre like that will work if the water is flat calm and the reflection symmetry is the main narrative of the picture, but in this case the rippled surface means it does not really work which means that my eye hits dead centre and stays there. If you want to move the building off centre, the sky and the water are too featureless so moving the composition upwards or downwards probably will not work; so maybe you could have moved it rightwards to have more geography and use the shoreline to bring the eye round the picture.

For me this is a 'close but not quite' image: I find the position of the white candle with its highlights quite distracting and the I don't know if it is my monitor but the processing has not done the skin colour/texture of her thighs any favours.

Nice first go, Andy. I like the composition and exposure is spot on.
You have already discovered the joys (ha!....the challenges) of a shallow DOF: the EXIF does not show what aperture you were using - something in the f11 range? If possible I would risk higher ISO to get the depth of field because you can always reduce noise with careful but you can't correct poor focus.
Despite that it is a shot well seen so good reactions! Just don't expect it to happen every time

Using handheld, a good camera technique is essential and there is one technique used by rifle marksmen where you inhale then exhale, but halfway you hold it then press the shutter button smoothly. It is surprising how you can improve your steadiness with practice.

When shooting macro even the merest breeze can move the main subject out of the focal plane so patience is a definite virtue. However if conditions are difficult, and if the light is good enough, you could try using the continuous shooting mode where you set the camera on the highest shooting rate, focus as best you can then rock ever so slightly backwards then forwards while gunning the shutter - it is not pretty but of the 10 or so shots you get, hopefully one is near in focus.

As for focus stacking, yes that is a very useful technique if the subject will stay still long enough. You can do this in one of two ways: change the focus point of the camera very slightly or change the position of the camera very slightly and for the latter you can google 'focus rails'.