What might skin cancer look like?

Growing sore. Skin cancer often begins as a small bump that looks like a “pimple that doesn’t go away”. It gradually enlarges, and sometimes bleeds. The cancer may appear red, pearly, scaly, flesh-colored, or darker than the surrounding skin. If you have a growing spot that doesn't heal, you should see your dermatologist.
New lumps or bumps. Any new skin bump which is new, enlarging, and changing is concerning. The older you are, and the more sun exposure you have had, the higher the risk of skin cancer. Melanomas risk is remembered as abcd: asymmetry, irregular borders, irregular coloration, diameter >6mm. If in doubt, have a doctor look at it.
Many types . Depends on the type of skin cancer: basal cell, squamous cell, melanoma, dermatofibrisarcoma, etc. They may look like a pimple, mole, ulcer, scar, nodule, plaque, rash, pigmented, colored, etc. Appearance as well as behavior and history and location are important pieces of information that contribute to the assessment.
Varies. There are several different types of skin cancers. Squamous cell the skin begins as a small nodule and as it enlarges the center becomes necrotic and sloughs and the nodule turns into an ulcer. Basal cell patients present with a shiny, pearly nodule. Melanoma patients have an irregularly appearing pigmented lesion.