Yes, I have some new rules from the last few months:
1. Don't buy anything on day 1 release.
2. Only buy new games many months down the line when they actually work.
3. Try to buy complete games, i.e. I haven't brought Witcher 3, even though I have both the originals (boxed) and really enjoyed the first.
4. Avoid InDev like the plague.
5. Only buy single offline games.

1. For games available DRM-free on PC on disc, buy the PC version on disc.
2. For games that don't meet the above condition and are available on disc on console (PS4, Wii U or Xbox One - I have all three), buy the console version on disc.
3. For games still available new at retail, give priority to new over used or digital.
4. For games that are only available digitally on PC or console, give priority to PC.
5. For disc-based games, pay no more than €60 (if I really want the game now of course - I probably buy a full-priced game once every two months at most, although I've been splashing a bit on Wii U games of late).
6. For downloadable-only DRM-free games (e.g. GOG), pay no more than €10.
7. For downloadable-only games only available with DRM, pay no more than €5.
8. For downloadable games that later come out DRM-free that I already have with DRM, pay no more than €5 for the DRM-free copy.
9. For past-gen used games on disc, pay no more than €10.
10. Where past-gen used games aren't available at a reasonable price as per 9, go digital.
11. For past-gen games, if no digital copy is available and no reasonable used copy is available, hoist the Jolly Roger and go abandonware.

Mine is quite simple:
Only buy a game if I'm really interested in it and if I feel the price is reasonable for that.

Works out quite well for me :D

Mine are:

1) never buy Steamed games

2) When I buy digital distro games, I buy GOG

1. Buy eveything on sale, I can afford, immediately.
2. Have a backlog so massive I would have to live millennia to complete it.

This.
Most of the time it's working out really well. :D

Doesn't matter if it's Origin, uPlay, or whatnot, as long as I'm enjoying the game everything is fine. :)

Always use protection and never kiss them on the mouth...wait.

1. Buy games.

drm free
linux version

1. For downloadable games, the game must not have DRM. This is a hard rule. (I don't buy physical games, but if I did, I would make an analogous requirement, and I have decided not to get any more region-locked systems, or any systems that support DRM on digital downloads.) Note that this rule applies to demos as well.

2. Game must run on Linux. (WINE is considered acceptable here.)

3. How much I am willing to pay depends on the type of game. If it is my favorite type of game (turn-based RPG with a player-created and changeable party that focuses on gameplay with little/no story), then I am willing to pay more. For types of games that are more of the periphery of my interests (like 2D platformers, bullet-hell shmups, and similar action games), the amount I'm willing to pay is less. Some genres (FPS, pure adventure games, stealth games of any sort, realistic sports games) I have no interest in and will not buy no matter what.

1. Serve the public trust.
2. Protect the innocent.
3. Uphold the law.
4. <classified>
5. <classified>
6. <classified>
7. PROFIT!!!

Buy them for cheap or... don't buy them.

1. Look at some gameplay to see if it's intresting, and form a little review in my mind.

2. Read at least 3 proper reviews, Seeing not only if it is good, but if it is my kind of game.

3. Must not be over $60. Period. Like with $90 Dork sauls 3 that went off my list.

4. Read a bunch of steam reviews, you can get a very good picture there of how the game is.

You nailed it for me.

I have the third one, though, if it's on USD, do not buy if there's other offerings. Exchange rates are deadly.