About 6 years ago I was doing this. I was pulling in several hundred $ per day getting members to join gaming subscription sites. It was paying $10 per signup. I would simply join an affiliate program at one of the 'MMORPG tip/tricks/cheats subscription sites' for whatever the popular game is. At the time the biggest and baddest game was Star Wars Galaxies. A few years ago it would probably be WOW, today i guess it's farmville.
Once I had my affiliate code, I would just download their squeeze pages and reupload them to my own domain name. I would make a bunch of changes to the site to bump up the SEO for my keywords (more on that below), swap out all of the buy links with my affiliate code, then I would then go around and get backlinks.
Finally I would setup a google adwords campaign and just let it go to work. Yes folks, that's all that it took to make bank only 6 years ago. These days you have to be a little bit more creative or you have to be one of the first to market.
My advice, look at upcoming game release dates and start early. Start building up web properties with keywords for your target game before it even comes out, then you will already have the google juice for your target keywords when the game launches.
I've moved on to bigger and better things now, so I'm happy to share all of my info here in hopes it can help someone else who is just getting into the gaming site niche.
Here is one of the adwords ads that was pulling a lot of clicks at the time:
Code:
Star Wars Galaxies Cheats
Updated daily! Only $25/yr
earn 160K-270K Credits per hour
mmog-guru.com/swg
and here are the keywords i was using. just replace 'swg' and 'star wars' with whatever game your going to promote
Code:
swg cheats
star wars galaxies strategy
star wars galaxies cheats
swg bugs
swg exploits
star wars galaxies trainer
star wars galaxies exploits
galaxies cheats
star wars galaxies bugs
star wars galaxies powerleveling
star wars galaxies macros
star wars galaxies power leveling
star wars galaxies skill gain
star wars galaxies jedi slot
star wars galaxies power gaming
star wars galaxies auctions
swg skill gain
swg strategy
swg jedi slot
swg trainer
swg macros
swg power leveling
swg powerleveling
swg power gaming
swg auctions
swg vault
guide ranger swg
server swg
guide hint strategy swg
forum swg
crafting swg
creature handler swg
guide swg
info swg
cheat swg
exploit swg
swg warcry
guide smuggler swg
skill swg tree
swg bug
artisan swg
calculator skill swg
stratics swg
I would put in the urls and site names for any competitor sites. I would also get keywords for the names of the servers / shards that people play on. Make a keyword rich page for {every class type in the game} + 'strategy' or + 'guide' or + 'cheats'
If I was doing this today and wanted to go a little blackhat to get lots of good keywords fast, I would scrape twitter feeds for the game name and shard names and repost those tweets on pages inside my domain. The google bots will come and it will look like people are talking about game related stuff on your site. You will rank high for your keywords.
I hope this knowledge was useful to you. Good luck!