If this is your first reptile, three species we'd actually recommend: leopard gecko, crested gecko, or corn snake. Bearded dragons are great too but they need more space, brighter lighting, and a more varied diet, so we'd put them in the "beginner-with-research" tier.
Leopard geckos: 20-gallon tank, no UVB strictly required (though it helps), eat insects, live 15–20 years. Calm, easy to handle, come in beautiful colors.
Crested geckos: even simpler — they eat a powdered fruit-based diet you mix with water, they don't need heat lamps in most homes, and they're very docile. A great first reptile if you live somewhere with mild temperatures.
Corn snakes: 20–40 gallon tank, eat one frozen-thawed mouse every 1–2 weeks, very calm, almost never bite. Live 15–20 years.
What NOT to start with: green iguanas (get 6 feet long, need a whole room, can be aggressive), monitor lizards (powerful, need huge enclosures, expensive to feed), hatchling tortoises (live 50–100 years, get big, need outdoor space), chameleons (extremely sensitive to husbandry mistakes), and any wild-caught animal.
Before you buy, do this: read at least two full care guides from reputable sources (Reptifiles, ReptiFiles, ReptileGuide, university extension sites — not random YouTube videos). Build the enclosure FIRST and run it for a week to make sure temperatures and humidity are stable. Then get the animal. The number one cause of reptile death in new keepers is bringing the animal home before the enclosure is ready.
And budget honestly. A leopard gecko is a $30 animal that needs $300+ in setup before it comes home. That math is normal. If the setup feels expensive, that's the right setup.