A: First off, there is likely to be an angry red color around the margins that extends anywhere from a few millimeters to several inches (reasonable size for a smallish cut 1-5cm). The area will be swollen, tender to the touch, and warmer than the surrounding skin.
The wound may drain blood, clear fluid, or pus or a combination of these. Pus colors range based on what the infectious organism is, and can include yellow, yellow-green, green, white, or tan/beige, but can also be tinted pink by blood getting into it. Blood from a wound that is infected will often be very dark or have clumps of pus floating in it.
The wound may form a moist-looking yellow scab or a dark, hard scab as it attempts to heal - these are both composed of dead tissue and the wound will heal faster and cleaner if they are removed and the wound bed is kept moist but not sopping wet. That said, constantly picking at a wound is a bad idea, too.
The best treatment for a small cut is to wash with soap and water, and cover with a clean dry bandage (and an ointment like Polysporin if modern era). Try to keep it clean and don't do what my son does and leave the bandage on for two weeks or until it disintegrates in the shower.
Large or deep cuts may require sutures or some sort of adhesive glue meant for surgical application (no, please don't use SuperGlue. It works like a charm, but non-toxic really isn't meant to read: safe to pour into open wounds). Again, washing the wound, keeping it clean, and keeping the wound-bed moist or the sutured cut dry will aid healing.
Infected minor cuts rarely turn into systemic problems, but if the red margin of the wound starts to look streaky or the red starts to follow veins in streaks, this is a sign of serious, potentially fatal infection of the bloodstream and needs emergent treatment. Likewise, a sudden, serious increase in pain, or severe swelling of the area can indicate serious infections.