Simple Combat Initiative

In a combat situation, every participant capable of taking actions rolls a single d10 and adds their Dexterity and Wits score. This is their initiative value. The highest value takes their action or actions first followed by the next highest and so on and so forth. This order stays in all subsequent rounds unless there is a break in the hostilities in which case all participants reroll their initiative.
In most cases related groups can use a group initiative. In a battle against a group of player characters, a necromancer and a horde of skeletons. The various player characters and the necromancer would each roll their individual initiative but for simplicity, all the necromancer’s skeletons would act on the same initiative rating.

There are two ways to roll initiative. Initiative can be rolled anew every round, or initiative can be rolled once and the same turn order can be applied in the every subsequent turn.
The former option is a little bit more realistic and dynamic while the second option makes combat take less time in the real world to figure out.
I recommend using the static initiative order when figuring out large battles and rolling initiative every round when figuring out duels or very small melees such as a group of adventurers fighting a single large monster.