Draw the default inspector for your SettingsProvider to save time!

GameSettingsProvider.cs

using UnityEditor;
static class GameSettingsProvider
{
	[SettingsProvider]
	public static SettingsProvider CreateGameSettings()
	{
		var provider = new SettingsProvider("Game/Settings", SettingsScope.Project)
		{
			guiHandler = (searchContext) =>
			{
				Editor ed = Editor.CreateEditor(ScriptableObjectUtilities.GetOrCreate<GameSettings>(GameSettings.path));
				ed.OnInspectorGUI();
			},
		};
		return provider;
	}
}

Normally you will want to supply the ScriptableObject yourself, but here is the GetOrCreate method for the curious:

public static T GetOrCreate<T>(string path) where T : ScriptableObject
{
	var obj = AssetDatabase.LoadAssetAtPath(path, typeof(T));
	if (obj == null)
	{
		obj = ScriptableObject.CreateInstance(typeof(T));
		AssetDatabase.CreateAsset(obj, path);
		AssetDatabase.SaveAssets();
	}
	return obj as T;
}