Plant your feet flat on the ground, toes slightly outward. Feet should be about shoulder-width apart. Getting below the bar, bending your knees slightly. The height of the bar must be adjusted for your personal body height. It is important to keep the weight on your heels but keeping your full feet on the ground. Refrain from distributing the weight to your toes or ball of the foot, as this is bad for your knees.
Feet too straight ahead tends to cave knees inward, so angling them out toward about 10 and 2-o'clock is useful (with "pigeon toed" or "toeing-out" feet, do your best to be stable, and do not use much weight). But, do not toe out more than that angle.
Do not stand with your feet further than shoulder width apart (too wide stance). That would bring your abductors (inner thighs) into the movement, which would cause stress to the medial collateral ligament (MCL), abnormal loading of stress on knee cartilage, and improper patellar tracking. Likewise, do not keep your feet in a close stance (too close together), as that can cause you to distribute the weight through your toes, which is bad for your feet and knees.