I love Photoshop, but I can't afford to get Photoshop on my home computer. So, I've been trying different sites for photo editing. So far, my favorite has been PicMonkey, but there are plenty of other photo editing sites out there as well that might work better. As long as you follow some basic rules and don't go overboard (unless you like the overboard look), they work just as well as Photoshop. However, you won't be able to edit anything out of the picture, or clone anything in the picture, or do any advanced editing to the picture without Photoshop (that I know of).
3 Basic Rules I Follow:
1. Crop first - some photo editing tools put barely-there borders around the photo to accentuate the center of the photograph. If you put the border around it first, then crop, it changes the look of the picture and you may not like it so much. I've found it's just easier cropping first.
2. Don't over-do it on the color. Sometimes, less is more. I'm guilty of this a lot of times, but then I learned, it also depends on the computer monitor you use. Make sure the computer you're using has a bright monitor, otherwise the pictures can be overloaded with color. If you're using a computer with a dull monitor, just be aware and try to either understate the photo or save the photo to a cloud-based site (like Dropbox) so that you can see what it will look like on a normal computer screen first before posting.
3. When using the tools provided by photo editing websites, always remember that there is a fade scale. If you like a certain way the tool works, but think it's too much, look around for a scale letting you edit how much of that tool you would like to apply to the picture.
And those, so far, have served me well (at least, in my opinion they do, which, when editing your own photo, is the only one that counts). :D