Best practices (Patterns) for "manager" script

I noticed that as my game assets grow, I’m starting to see a need for a script that is not necessarily directly linked to a game object, but is responsible for managing attributes and/or behaviors of a group of game objects.

Say, there are multiple scenes in my game, for instance, and I can create an individual script for each of the scenes to address the need for any given scene. But, what would be a sensible way to manage attributes, references, even methods that are commonly found/used in all scenes?

Any tips, links, or code samples in C# will be very helpful.

I can share this solution I found somewhere:

using UnityEngine;
using System.Collections;

static class Manager {

	public static Initialize initialize;//A script on the GameCobject called Manager

	public static GameObject playerCamera;//some gameObject called Player Camera

	public static GameObject managerObject;//some gameObject called Manager that has other "helper" scritps on it
	public static GameObject player;//some gameObject called Player

	// when the program launches, UtilityManager will check that all the needed elements are in place
	// that's exactly what you do in the static constructor here:

	static Manager() {

		managerObject = safeFind("Manager"); // (some persistent object)
		initialize = (Initialize)safeComponent( managerObject, "Initialize" );

		playerCamera = safeFind("Player Camera"); // (some persistent object)

		player = safeFind("Player"); // (some persistent object)

		// etc .. 
		// (you could use just the one persistent game object, or many - irrelevant)
		// PS. annoying arcane technical note - remember that really, in c# static constructors do not run
		// until the first time you use them.  almost certainly in any large project like this, UtilityManager
		// would be called zillions of times by all the Awake (etc etc) code everywhere, so it is
		// a non-issue. but if you're just testing or something, it may be confusing that (for example)
		// the wake-up alert only appears just before you happen to use Grid, rather than "when you hit play"

	// this has no purpose other than for developers wondering HTF you use UtilityManager
	// just type UtilityManager.SayHello() anywhere in the project.
	// it is useful to add a similar routine to (example) PurchaseManager.cs
	// then from anywhere in the project, you can type UtilityManager.purchaseManager.SayHello()
	// to check everything is hooked-up properly.
	public static void SayHello() {
		Debug.Log("Confirming to developer that the UtilityManager is working fine.");
	// just some convenience routines to save people copy pasting 
	// when GameManager wakes up, it checks everything is in place...
	private static GameObject safeFind(string s) {
		GameObject g = GameObject.Find(s);
		if ( g == null ) bigProblem("The " +s+ " game object is not in this scene. You're stuffed.");
		// next .... see Vexe to check that there is strictly ONE of these fuckers. you never know.
		return g;
	private static Component safeComponent(GameObject g, string s) {
		Component c = g.GetComponent(s);
		if ( c == null ) bigProblem("The " +s+ " component is not there. You're stuffed.");
		return c;
	private static void bigProblem(string error) {
		for (int i=10;i>0;--i) Debug.LogError(" >>> Cannot proceed... " +error);
		for (int i=10;i>0;--i) Debug.LogError(" !!!!!  Is it possible you just forgot to launch from scene zero.");