This is what I did in my kitchen and it came out perfectly (the tile guys had better close their eyes now). I went to the craft store and bought some 1/8" thick balsa wood strips and I drew lines on my wall where I wanted the glass tile stripe to be. I then tacked up the balsa wood to mask the stripe. I used drywall compound to build up the 1/8" thick stripe because it was my backsplash and wasn't going to get wet but if I were doing this in a bathroom I'd use thinset. Basically I used a flat putty knife to fill the space between the two pieces of balsa and when I was done and it was dry I had the perfect "platform" to lay the glass tile on. I did it this way because I knew I did not have the practice, skill, or the "touch" to build up thinset on the fly under the glass tile. I do have pictures of my method somewhere if you need them, I'd have to dig them up but I can do that. I was REALLY pleased with how it came out - the thinner glass tile when set is perfectly flush with the thicker field tile.

Could be worse! Most of what you showed really isn't that bad, except for the very last picture. That one's pretty bad. Other than that, there might be a 1/2 dozen pieces of tile that you've marked that I'd say go beyond what can be expected. Keep in mind, if you get that close up to ANY tile, you're going to see all kinds of chips and/ or imperfections along the edges that would make your hair stand on end. Especially with a medly like that, the idea is to stand back and take it all in as a whole. I'd HATE to show you some of the sizing pictures I've taken of the work I've been doing over the last few weeks at this hotel I'm doing!! Pieces of Jerusalem stone as much as 1/8" difference in size from one piece to the next, and we're using an 1/8" joint!! There are areas where I've had no choice but to cut the factory edges off in order to be able to use pieces of tile, and other times where I've had to throw whole sections of a wall out of whack to make it look GOOD! One thing I've found in the few jobs I've done with glass tile-- although they're not all as rustic as what I just showed (it's supposed to be like that, kinda resembling sea glass), I've yet to come across any that DIDN'T have alot of the small chips and dings that you show above.

Well mine is actually a mix of extra tiles I ordered for the kitchen backsplash (long story short...they're the pieces that I should have ordered bullnose) and they're too expensive to just let sit in a box, so I thought I'd do a backsplash on the desk to remind me how stupid I was for the rest of my life LOL But since they're not bullnose (they're handmade tiles) I needed an edge for them, and didn't want to spend a fortune so I purchased some really pretty little glass tiles to go on the top and near the bottom two little tiles deep. But frankly, that's hand made tile AND glass tile LOL Bill and Mongo have made me so danged tile crazy (in a good way) that it sounded like a fun project for the future...but maybe not heh heh As I typed this I got a new email with my tile install bid...CHOKE ummm $17,900....Ouch. Maybe I can tackle this little job LOL

You wouldn't like random, but you can achieve it by using a random number generator. They have them on the web. Or you could roll a die. You might also try using the Fibonacci series as a way of spacing the tiles. That describes a great many structures in nature. To the human eye it looks random but pleasing, even though it's not random at all. Your Post-It method should work. Just make sure when you put them up that they're spaced correctly, not so much for the grout lines, as to have the right number of them up and down. Make sure you measure your tiles because nominal 4"x4" are often not that exact size. Instead of the papers, you could use a chalk line (string filled with chalk) to quickly draw where the grout lines will be (remember to include coves, bull noses, etc.), and then just use your 1x1's. If you have a better imagination for positioning than color, you could arrange the actual tiles on the floor as they'd be on the wall. If there's some color variation in the tiles, that's worthwhile anyway. What I do, is start with the view of the whole and put in the first 3-4 to break it up into sections, then start filling in. Sometimes move one this way or that to keep the harmony going. It's much more wholistic than using a numerical rule, but more fun. :)