I often choose the winner via random.org but the odds of winning aren't equal. People who gave answers I like might get another entry while others might not be entered at all (for example if someone just won another giveaway of mine, I might decide that I want to give the prize to someone else). I never promise a specific method of choosing a winner.

As Mr. Misteryo said: "It's your giveaway, give it away the way you want to! "
I'm ok with that, but we are asked for our opinion in this thread so...
...here's my 2 (euro)cents:

I've been participating in GOG giveaways for little less than 2 weeks now, won several games, not as much as I'd like of course, but I'm not greedy and I'm happy with what I got. You could say I'm really touched with the number of kind souls dwelling here that are eager to provide many others fellow gamers with free games. My hat down, kind sirs!

1cent - Ninja giveaways
I'm wondering are the lurkers from there even PLAYING games or are grabbing whatever they can just to pile up games for whatever reason. I mean, if you're 24/7 in that thread you're certainly not playing anything you snatch there. I'm talking silent ninjas, not those people who say "thank you for this and that" or ask kindly "can I have this, I would like to play it", that is ok in my book. So, my advice to people giving away games there: "Ask if someone want the game you're giving away and give those games to those who either answer in topic or PM you."

2cent - Individual topic giveaways
I REALLY hate random.org! There, I said it. Moving on.
Don't have any problem with restrictions like rep or join date for giveaways. It's ok to narrow your selection like that.
Don't have any problem with "I'm in/post anything" giveaways in combination with random.org, it's pure luck and that's ok.
But, I have HUGE problem with "write something interesting/prove you want to play this game" giveaways in combination with random.org. Why oooooohhh WHY, are you doing that, it just doesn't make sense?! People who really like to play the title enter the competition and they are beaten by some guy who entered with no emotion and is probably not even going to touch the game, maybe trade it at best. NO, PEOPLE! PLEASE STOP DOING THIS!

Not once have I entered any giveaway for any game that I don't intend to play, nor will I. I'm not saying I'm going to play it right away, but one day that game you have given me will get the attention it deserves.
I can only hope there will more people who will RESPECT THE GAMES and RESPECT THE GIVEAWAYS in this manner.

Peace out.

Another interesting option!
I think I'm leaning towards events that have some degree of interaction with the contenders. As such, a hand-picked winner (or winners) would be required, and that decision process would ultimately be very subjective. Leaving a little wiggle room seems reasonable in that situation.

Please don't make a habit of bumping giveaway threads unless they have content in them that people might want to see (unanswered question / unfulfilled request for help, creative contest entries, etc.) You still only have X games / X money to spend.

And pretty please with a condiment of your choice on top, don't "give away" codes that aren't actually legit. It's not "generous" by any stretch of the imagination. Even "go pirate it" is ultimately better because a pirate might want to acquire a license later for convenience/completionism, but the recipient of a trash code is actually prevented from buying a legit game.

As a purely abstract matter, you might want to consider banning trading if you're giving away your favorite game (when the intention is to reward a fellow fan of the genre/franchise with a specific game), because trading works out to you gifting abstract free money to a lucky entrant and the end player "buying" the game with some of their capital.

I must admit, I sometimes check out the ninja and even the gifting threads and I have wondered at the same thing! Why stockpile games you know nothing about and might not even enjoy? But, to each their own. We are lucky to have such an amazingly generous community here, and it's one of the reasons I'm so eager to learn what kinds of giveaways you guys and gals would most enjoy. =)

Oh, I can definitely see you point there! But choosing how to award the gift(s) seem like the hardest part of a giveaway to me. How exactly does one determine if Person X is more deserving, or wants the game more, than Person Y? I realize that I'm probably just overthinking things, but it makes me nervous, and it would be oh-so-convenient to turn those tough decisions, and the blame, over to mr. random.org. ;^)
Don't worry though, I'm currently trying to think of a creative method of selecting the winner(s), perhaps by including a panel of judges. (Which would definitely help to ease my guilt, if nothing else!) Anyway, thanks so much for your post!!
Hey there! I'd like to touch base with you a little more, so I'll be sending you a PM. Hope you don't mind. =)

As by chance, I made my first GA yesterday evening, and I decided to give the possible participants some hints on the name of the games I gave away, and the first one who guessed and posted a name, got the key for it.

I think it was more fun that way, instead of just putting out the keys or just let people post "I'm in!" and then choose winners randomly.

I also think, it makes games more valuable, if you have "to earn" them, instead of just grabbing a key.
And regarding the reactions to some of GOG.com own Give-Aways, people enjoy to do some brainwork to win new games.

The only thing, I would (will?) change for future GA's - I will make 'em harder...all the keys were taken in less than an hour, which really took me by surprise.

But then,...it was a GA of games available in a very recent bundle - so, I guess the next ones will be chosen independent from a bundle...

Regarding rules to enter/participate: I did have some on my GA, because I think the more clearer the winning conditions - the better.

In that way there is no (or at least: less) room for complaints, if someone doesn't win.

Restrictions per Rep, and / or Join Date I didn't apply, because that doesn't make sense to me - why restrict certain people from winning, only because they weren't around when GOG.com started, or only because they don't log in on a daily basis and comment in the forum?

All in all I can say, doing a GA was fun...and I think, I will repeat that somewhen in the future.
I'm actually already thinking about the way I will do that second GA - keeping in mind that it should be:

- a challenge,
- funny,
- enjoyable by as many GOGfellows as possible.

Three points that - if you do your own GA - will help to make it a success, I'm sure.

As long as you don't spam the forum with them I think it's fine, by that I mean if you have multiple games to give do so in one thread instead of making one for each game.

Hey there! You touched on some good points here. I have been toying around with some ideas for activities to include in my future giveaway(s), but I've not come up with one that I'd positively delighted with, and I think that may be due to the lack of real challenge for the participants.

I will only ever be holding contests for GOG games, with perhaps one exception for a very near-and-dear to my heart Steam game, one which will likely never be offered in a bundle or even go on sale, so I'd like to make sure that the games go to someone who will really love them, ya know? (Hope that doesn't come across as too selfish or demanding.)

Adding humor is another wonderful suggestion! I regret that I'm not naturally funny, but with enough time and research I may be able to make some of you giggle. ;^) Thank you so much for sharing your thoughts!
Point taken, I definitely don't want to intrude or cause anyone frustration. Giveaways should be fun for those who wish to partake in them without being a burden for those who don't. =)