Lizardmen 101
If an enemy unit has powerful stat lines, send Skroxigors at it. Skinks are so puny and poorly skilled that high strength high weapon skill attacks will be wasted as well the Stomps (if there are any). Kroxigor hit hard enough to wound most things.
If an enemy unit is mediocre stat lines, send Saurus at it. They are strong and tough enough to wound most things easily without taking many wounds themselves and they enjoy an extra attack and good saves.
While you are waiting for close combat to happen, shoot things. Use Skink shooting at whatever the most powerful low armor save units on the other side are. Use Salamanders at any enemy units tightly packed.
If you don’t want to kill something, redirect it with sacrificial Skinks or tar pit it with a big Cohort. Swarms can stall or redirect things too but not as effectively.
Razordons are not cost effective for offensive fire, but they can be used to defend your other shooters though this is optional.
If there are war machines, send Chameleon Skinks and Terradons at them. If your Skirmishers, Salamanders, and Razordons are out of better things to do, they can charge war machines too.
Support your Saurus and Skroxigor with flank attacks from Stegadons, Cold One Cavalry, smaller blocks of the same infantry, Kroxigors, and Salamanders/Razordons that have run out of things to shoot at.
Big dinosaurs attract heavy artillery. This can be mitigated slightly, but there is no easy fix. This is just something we have to live with.
A Slann with the extra power die discipline will get lots of spells off very effectively. Slann are the most powerful unit we have, but our lists can still win without them. There is no best lore but make sure whatever lore you take that you have a use in mind for most of the spells in it.