If you get the Slayer task to kill Desert Lizards you should not skip. It can be a lucrative task to complete because they are easy to kill. For low, to mid-level players, this is a definite must-do task. It takes very little time to complete, and you would rarely get assigned to kill too many of them. The only requirement you need for this task is Slayer level 22.

Inventory

Waterskins. You take damage from the heat in the desert. The Waterskins will help you mitigate the damage. However, they need to be refilled by using the water fountain in Zanaris.

Ice coolers. These will be needed to throw at the Desert Lizards to finish them off. 

Food. You need food to manage your hit points.

Superset. Using a Superset will help you kill the lizards faster.

Location

Desert Lizards can be found east of the Kharidian Desert or southeast of Shantay Pass.

The easiest travel means to get to the location is to use the magic carpet to Uzer, and from there, you need to head southwest.

Alternatively, you can use the Fairy ring code DLQ.

How to Kill Desert Lizards

Desert Lizards are weak to all types of damage and attack styles. Preferably, you will want to use a melee setup. The Waterskins are mandatory, but the Ice coolers you can do without. However, as you attack Desert Lizards, you can use Ice coolers when they are low health. The Ice Coolers will finish them off.

There is no particular way in which you should tackle this task. All you have to do is get to the location and start killing them one by one. It is easier than to attack a bunch of Desert Lizards at the same time. Keep in mind that they can also be killed with a ranged setup. Desert Lizards have a melee-only attack style, but there is no way to safespot them.