>>1876
for something like that, i'll just go look at how artists actually draw something like a building being roughly handled, and try to figure out the best looking, most economical way to copy it onto a collage.
of course different artists do it different ways, so just try to find what's best for what you've got going on.

for basics;
- add cracks/visible damage around the spots where the toes are touching the building. on the layer above the building but below the toes would look best.
- you can also try adding little bits of cracked glass to other parts of the building too to show it's under stress.
- i wouldn't go crazy with dust, but definitely add a tiny bit. if you draw it right, you can make it look like it's billowing out from under her toes, which would be a big plus to making it look "real"

for more time-consuming stuff;
- if you want to, a huge thing you could do is to actually split the building layer into two by drawing a strongly jagged line across it horizontally, and then very slightly move and maybe play with perspective so the the top half looks like it's getting pushed outwards and to the left a little bit. IE, to give the look that the building is being broken in two by her playing with it. i think this is important because by default, it kind of looks like her 2nd and middle toes on her left foot are intersecting with the building.

- if you did that, you can either cover up the now empty parts with dust, and/or look for another ochiko picture where he's drawn the bottom of a broken building and try to use that to cover the empty space

- you can try moving her right foot back a little bit, and rotating so the toes look they are more convincingly touching the building. the big toe looks great in that, but the other ones appear more superimposed.

- you can edit it so the building is actually getting just slightly compacted by her digits (check my dubs) pressing into it, like the boat in this picture. in general this probably also shows a good way to show the cracks/dust, but it's up to you.

as for clouds, i just copy and paste them from different pictures. usually just freestyle select a cloud, shrink the selection a bit, heavily feather, then play with the lighting/values until it looks mostly white and still has detail, then smudge the remaining blue parts. you can save the end result to re-use later.

it's all personal preference with how much effort you even want to put in. a big advantage to collages is how fast you can put them together, so it's understandable if you don't feel it's worth the effort to do a bunch of minor adjustments to make it just slightly more real.