First, the tools.
I started by using this area to remove the bug with the clone tool. (To use the clone tool, select it from the palette, hold down the Alt key [the tool will turn into a target] to select the area you want to clone. Release the Alt key and move the tool to the area you want to change and start clicking away. I find it much better to click rather than drag the tool, unless I'm doing long, straight stretches of cloning.) I used the size 9 soft round brush for this cap if I'm not mistaken.
Next I extended this line, branch, whatever it is with the clone tool and then smoothed it out with the smudge tool.
Then I used the clone tool to replicate the pattern on the left onto the blank side on the right. The arrows point to areas where the pattern is the same.
(and not very well, even.)
A few other examples
Getting it exactly right isn't always as important as making it look plausible. As you can see here, the jacket fold turned out rather different, but would you ever have noticed that that wasn't how the fold was originally if you hadn't been told?
With stuff like foliage, random is often better. Choose different points of origin for areas right next to each other, or a pattern will start to emerge, and nature is never that orderly.
Here I just built and built on the image until I could get a center cropping on Veronica with Logan still in the image. For the sky I just used a fill layer with the same yellow color. The shadow on the ground was built up with each layer.
This one took a lot of steps.
First I removed the bug. As you can see, her shadow turned out a bit different from the original.
Then I extended the top of the image using the clone tool for the most part, but for the window over the door I used the rectangular marquee tool to copy a section of the window and then pasted it and transformed it using Ctrl+T.
Next I smoothed the walls using the polygonal lasso tool and the smart blur filter and fixed the corner of the frame.
The wall still looked wrong so I used the clone tool to extend the shadowed area of it, and I fixed the corner of the frame some more.
Here I extended the top of the image using the clone tool.
I removed the top of the lamp and using the section underneath the lamp, judged how much wall there was before the painting started.
Extended the painting using a portion that was visible, then fixed the top of the lamp.
I guess the important thing with the lamp is to think about how something is supposed to look. I suck at creating perspective, but I can usually tell when something looks completely off, so for me it's mostly trial and error.
Here I worked a bit differently. I didn't use the clone tool, instead I copied the image and moved it around. Here you can see that the right side lines up...
Here's the left side.
Oh, and I think I lied, because I seem to recall using the clone tool to finish off the middle.
Even when doing something seemingly uniform, like a sky, I prefer using the clone tool, because there are subtle variations in color. When you're doing lines of cloning, holding down the shift key helps to keep them straight.
Here I used the polygonal lasso tool and the smart blur filter to get a smooth surface, and then I added a color fill layer with the non-sky areas erased. The fill layer opacity was also lowered to 30%
I finished with painting the upper part of the image in the same color as the sky with a large soft round brush (probably around 65) set the blending mode to Multiply and decreased the opacity until it looked natural.
Even more examples, this time sans commentary
Any questions? Just ask.