Hello:
Leopard Geckos are a great first lizard though I would go with one at least a couple months old. There are lots of color variety in them and they are also easy to house and feed. They don't require all the UVB that diurnal lizards need though you should have a day/night cycle for them. They can tame down faily well and can live for nearly twenty years. There's lots of care info on this site so you can spend some time checking it out. They are also a nice size, growing to about8-9" on average. Some may be a little larger but not by much.
Blue Tongue Skinks can also make a great first lizard though you want an Australian one over an Indonesian as the Austalian ones are a bit more even tempered. They grow a bit larger, up to two feet in length, but they are easy to keep and will eat just about anything.
There are lots of other great Lizards but for a first time lizard these are probably the easiest to start with.
Good Luck and Have a Great Day!!!