Go handle some. You can't order something online as a guess and have a reasonable expectation of what you're getting.
The numbers describing the binocular, like 7x35, gives you the magnification factor and the objective lens diameter, which is basically a measure of how much light they capture. (Bigger first number is higher power, bigger second number is brighter image.)
Two main kinds of focus control, a wheel or a rocker. Rocker is fast, but imprecise. Wheel is precise, but not fast. Depends on what you're looking at. Scouting game for a hunt, you might want the rocker.
You get what you pay for in binoculars, or more precisely, you don't get what you don't pay for. Cheap binoculars will have a large amount of distortion, especially chromatic, which puts a color edge on things in the image. Sometimes the two lenses don't quite match up, giving you a blurry or even slightly doubled image.
The intended use also determines the size. You don't want 12x80 glasses to go birdwatching with. The field of view is so small you won't be able to track anything.
