To try and answer some of the questions -
Sorry the only pictures I took are the ones shown here.
The simple one first - the net curtains are just a picture from Google - type Net curtains into the picture search. As I had no intention of lighting or detailing the inside of the house having something that totally blocks the view inside is ideal. They are just printed and spaced about 1mm behind the glazing. What doesn't show in the photos but did seem to work very well was the garage side window. I wanted it filthy so I made some very dilute sandy coloured paint (humbrol 121) and put a smeary wash over the inside, then with the brush fairly dry touched the middle of the panes, it really looks as if someone has just rubbed a patch of dust off.
Now the weathering. This really did turn out to be much easier than I thought. It is mainly done with a black powder with a bit of light brown mixed in to tone it down a bit. I initially apply the powder with a paint brush but that is not stiff enough to rub it in evenly so I used a Tamiya Weathering Sponge like this.
I have heard that makeup brushes work but I haven't tried one.
For the water stain from the drain pipe and the bottom of the garage doors I needed the colour to be much more intense so I used a paintbrush slightly wetted with a bit of white spirit. This makes the powder stick together and so is much denser. As the white spirit evaporates the edges can be feathered out with the sponge if required.
Along the bottom of the walls is some green powder but its not a great colour so I hid most of it with some green turf, might have to get a different colour.
I also used some mid grey powder in some areas just for a bit of variation. That is one of the main effects to try and get, lots of variation in shade and shape of the patches. But it is variation in shade not a rainbow of colours, There are only 4 colours for the bulk of this black, brown and grey with the bits of green around the bottom.
The window frames were done with very dilute matt black paint. This was mainly to put in the joints but a bit smeared on the frames also helps with the general griminess.
The most important thing with everything shown on this house is that there is no magic or special skill. It just needs a bit of care and patience and the willingness to give it a go. You also need to think ahead about the effect you want and what details you are going to add. As you can see the blocked up windows, the fallen off rendering (thats just made me think I should have had a pile of rendering on the ground), the paving and the doors all had to be planned before anything was constructed.
As for comments about feeling inadequate, just think that about 10 years ago I was happy making superquick kits so if I can change to this so can anybody. I wish I had found a forum like this where I could have picked up tips so if you want to ask any more questions please do. I can only say how I might do something, it doesn't mean its the best way as I still have a lot to learn.
Stu