How can i improve this 750pt lizardmen army?

There is no real reason to give the two scar vets spears unless you are mounting them on cold ones. On foot they allow the model to fight from the back rank, and as characters they will have to be in the front rank. You'd be better off giving them lt. armor. Also for a hero level character I am more partial to the Burning Blade over the sword of the hornet you have on the other Scar-vet.