Welcome to the forums!
Whatever game line you play. It's also okay if you just like writing and/or painting.
As for painting I prefer a middle ground between painting every regiment different and painting the army one color. My Lizardmen have a caste system.
Worker Skinks are light blue, tan, with a dash of dark blue therefore their Kroxigor spawn kin are also similar. All my cohort Skinks are this color.
Warrior Skinks (Sotek caste) are light green with bright red crests. All my Skirmishers are this color.
Beast caste Skinks are dark green with dark red crests. My Salamander handlers, Terradon riders, Stegadon crews are all this color. Also my Skink Priests with Lore of Beasts use this color.
I have two different colors of Saurus, based loosely on the common Skinks. Light blue with dark blue backs and yellow spots. Jade green with dark green backs. The idea is the blue Sauri work with Skinks more closely and the green ones are more aggressive not I try to limit myself on the battlefield like this. Lately I tend to take one regiment of Saurus Warriors, not two. My original plan was to paint my Temple Guard in a more regal shade of blue with a similar spot pattern to the blue Saurus and make my Saurus cavalry a darker shade of green with a splash of red to match my beast Skinks but it may be a very very long time before I get around to painting Saurus Cavalry.
Apart from a few designated for carrying Saurus characters, all my rank and file Cold One riders have been converted to zombie Cold Ones to use as "dire wolves" in my jungle themed undead army. My Saurus Cavalry riders are waiting for me to get a hold of Dark Elf Cold Ones. Also they are waiting for me to opt to use Cold One Riders in numbers again. I can't put my finger on why, I'm just not a fan of that unit. I can't justify painting COR when my Temple Guard are all unpainted, and I use Temple Guard practically every game. Wow tangent.
A few other ideas. Some painters have gone with themed sets. Usually based on terrain. We have desert themed, snow themed, volcano themed, and aquatic themed lizards. The Kings of War Salamanders which are their answer to Lizardmen are encouraging a fire-theme since Salamanders have a lot of fire powers and are fluff-wise tied to the element of fire.
Less common is to do a theme based on historical group or era. I've seen Samurai Lizardmen, Graceo-Roman Lizardmen, and Zulu Lizardmen.
Another option I've seen is for every model or nearly every model to have a different color scheme. It's slow going but it looks good in the finished product stage.
I apologize for not having links. I'd just recommend going through the
general painting forum and
army blog forums and seeing what you like and what you don't like.
