ooooh. I like the
OOP models, good stuff!
With what you have you have a lot of options here. I would suggest getting to army book as your next purchase if you don't already have it.
What I can suggest is this:
At 500 points you are going to want to use most of those Skinks. Four units of ten Skink Skirmishers will go for 280 points. That gives you room for a character or two and maybe a Sallie or a Razordon (which you don't have). A decent list would use a small block of Saurus, two or three units of Skinks a Scar-Vet (maybe) and a Razordon or a Sallie.
For 750 I would just add the Steg to the 500 and maybe mount the hero.
At 1000 you have more options. That can be up to you really. At those points you can get into more things that make the Lizardmen tick like an EotG or some CoC.
Honestly, with these models you could get to 1500 easy!
If you want to learn the basics you are going to want to use some Saurus blocks to learn maneuvering and such.
Logically, you are going to want to purchase a few things to round out this force. Getting a Slann would let you make a decent-ish army at 2000 points. After that, you are going to want Terradons (like Airmaniac said), Sallies/Razordons and some CoC (or Kroxigor). Another investment later could be a battalion box, it's a decent deal. Sadly the since these are the older models they might mash with the newer ones. It's not too bad, though, I have some
OOP Saurus that I got off Ebay a while back and they don't look half bad next to the new ones.
