List of instances of a custom class?

I’m trying to create a list of instances of a custom class. What is the correct way to do this?

In the Awake or Start of that script, make it add itself to either a static list on that class or a list on another object/class.

in C#:

using System.Collections.Generic;
using UnityEngine;

public class CustomType : MonoBehaviour{
   public static List<CustomType> instances = new List<CustomType>();

   void Awake(){
      instances.Add(this);
   }
}

Alright, I’ll try that. Cool, thanks.