Whats the best practice to draw GUI control buttons?

I need some GUI control buttons (left / right / jump / attack) for my jump and run game on mobile devices. And of course additional GUI textures for health / points and stuff.

These elements should be correctly scaled through different resolutions / aspect ratios. (not stretched, only resized to fit the resolution / repositioned to fit the aspect ratio.

What's the best way to do that? In my first game, i used GUITexture / GUITexts, but that seems to be obsolete by now?