Since many people were asking after the R9 280x review I guess it would be a good idea to post and somewhat summarize simple steps to optimize your PC game-settings. Feel free to chime in, post your tips/opinions on the matter and correct me if you think that I'm talking utter bollocks.
So, what do you want when playing games on your PC? First of all, getting an acceptable and playable frame rate is the number one priority IMO. It doesn't matter how pretty your game looks, if you're playing a slideshow it simply won't be enjoyable. Getting constant 60+ fps is ideal, obviously, but you will have to determine for yourself what is still "playable" to you and where you want to sacrifice graphics for performance, or vice versa. For many games I'd say that "playable" means constant 40+ fps for me.
In terms of cutting some corners to get an acceptable frame rate and still getting the best image quality there is a simple hierarchy: native resolution > texture quality > antisotropic filtering > lighting/shadow effects > anti-aliasing > ambient occlusion. Of course you will always try to find a good middle ground, but I think this could help when you have to decide what to turn down.
Being able to play your games at your monitors native resolution will simply give you the best backbone for all other settings. It prevents a blurry image, you don't have to rely on interpolation and the level of detail that you get far outweighs the potential fps increase you would get by dropping the resolution.
Texture quality affects the whole game, it is the skin that you will be looking at the whole time. I'd always try to achieve the best or second best texture quality possible with my system. Dropping other settings in order to achieve that is totally fine with me.
Antisotropic filtering also affects the textures, you should always try to get some degree of AF going. You don't have to max it out, but it is definitely important if you want to have the full benefit of your high res textures and if you want to be immersed in the world.
Lighting and shadow effects can look pretty good, but you can definitely live with lower settings here. The differences between ultra and medium/low usually aren’t as drastic as in other settings and they can be CPU-hogs sometimes.
Anti-aliasing is one of the most demanding settings usually. It can easily cut your fps in half if you decide to go with 4x msaa or another similar setting. Depending on the implementation it can also eat up crazy amounts of VRAM. If you have fps issues I'd always try lowering the AA or maybe switching to a faster version (like FXAA) to drastically improve your fps. Faster AA usually produces blurry edges, while no AA will leave you with jaggies on most corners. Pick your poison, but it is one of the most intense settings and can easily turn a game from unplayable to totally fine.
Ambient occlusion is one of those settings that you only really see when you look at comparison pictures, if you ask me. Yes, the dynamic shadows look nice, but it is also fairly resource heavy and you will probably not notice the difference when you're not actively looking for it. Turn it down or even completely off if you're not satisfied with your frame rate.
So, that's my newb guide for new recruits to the master race. I hope it can help some people and maybe explain a few things in the options menu. You can take it as a guideline if you're having performance issues and hopefully find the best settings for your setup, while maintaining the best possible visuals.