diff --git a/lib/firebase-app.js b/lib/firebase-app.js
index 6efc1f0c..efeda6a8 100644
--- a/lib/firebase-app.js
+++ b/lib/firebase-app.js
@@ -1,7 +1,6 @@
 import { NativeModules } from 'react-native';
 
 import INTERNALS from './internals';
-import { capitalizeFirstLetter } from './utils';
 
 import AdMob, { statics as AdMobStatics } from './modules/admob';
 import Auth, { statics as AuthStatics } from './modules/auth';
diff --git a/lib/firebase.js b/lib/firebase.js
index 5dc4882c..f38ea764 100644
--- a/lib/firebase.js
+++ b/lib/firebase.js
@@ -4,7 +4,7 @@
  */
 import { NativeModules, NativeEventEmitter } from 'react-native';
 
-import { isObject, isString, capitalizeFirstLetter } from './utils';
+import { isObject, isString } from './utils';
 
 import INTERNALS from './internals';
 import PACKAGE from './../package.json';
@@ -28,6 +28,10 @@ class FirebaseCore {
     this._nativeEmitters = {};
     this._nativeSubscriptions = {};
 
+    if (!FirebaseCoreModule) {
+      throw (new Error(INTERNALS.STRINGS.ERROR_MISSING_CORE));
+    }
+
     for (let i = 0, len = FirebaseCoreModule.apps.length; i < len; i++) {
       const app = FirebaseCoreModule.apps[i];
       const options = Object.assign({}, app);
@@ -63,9 +67,11 @@ class FirebaseCore {
     const _name = (name || INTERNALS.STRINGS.DEFAULT_APP_NAME).toUpperCase();
 
     // return an existing app if found
-    // todo flag as deprecated - no longer need to initialize native apps
     // todo in v4 remove deprecation and throw an error
-    if (INTERNALS.APPS[_name]) return INTERNALS.APPS[_name];
+    if (INTERNALS.APPS[_name]) {
+      console.warn(INTERNALS.STRINGS.WARN_INITIALIZE_DEPRECATION);
+      return INTERNALS.APPS[_name];
+    }
 
     // only validate if app doesn't already exist
     // to allow apps already initialized natively
diff --git a/lib/internals.js b/lib/internals.js
index 7dba8909..6b378a25 100644
--- a/lib/internals.js
+++ b/lib/internals.js
@@ -5,6 +5,23 @@ import SyncTree from './utils/SyncTree';
 
 const DEFAULT_APP_NAME = Platform.OS === 'ios' ? '__FIRAPP_DEFAULT' : '[DEFAULT]';
 
+const NAMESPACE_PODS = {
+  admob: 'Firebase/AdMob',
+  analytics: 'Firebase/Analytics',
+  auth: 'Firebase/Auth',
+  config: 'Firebase/RemoteConfig',
+  crash: 'Firebase/Crash',
+  database: 'Firebase/Database',
+  links: 'Firebase/DynamicLinks',
+  messaging: 'Firebase/Messaging',
+  perf: 'Firebase/Performance',
+  storage: 'Firebase/Storage',
+};
+
+const GRADLE_DEPS = {
+  admob: 'ads',
+};
+
 export default {
   // default options
   OPTIONS: {
@@ -17,15 +34,50 @@ export default {
   },
 
   STRINGS: {
+    WARN_INITIALIZE_DEPRECATION: 'Deprecation: Calling \'initializeApp()\' for apps that are already initialised natively ' +
+    'is unnecessary, use \'firebase.app()\' instead to access the already initialized default app instance.',
+
+    /**
+     * @return {string}
+     */
+    get ERROR_MISSING_CORE() {
+      if (Platform.OS === 'ios') {
+        return 'RNFirebase core module was not found natively on iOS, ensure you have ' +
+          'correctly included the RNFirebase pod in your projects `Podfile` and have run `pod install`.' +
+          '\r\n\r\n See http://invertase.link/ios for the ios setup guide.';
+      }
+
+      return 'RNFirebase core module was not found natively on Android, ensure you have ' +
+        'correctly added the RNFirebase and Firebase gradle dependencies to your `android/app/build.gradle` file.' +
+        '\r\n\r\n See http://invertase.link/android for the android setup guide.';
+    },
+
+
     ERROR_INIT_OBJECT: 'Firebase.initializeApp(options <-- requires a valid configuration object.',
     ERROR_INIT_STRING_NAME: 'Firebase.initializeApp(options, name <-- requires a valid string value.',
 
     /**
-     * @param moduleName
      * @return {string}
+     * @param namespace
+     * @param nativeModule
      */
-    ERROR_MISSING_MODULE(moduleName) {
-      return `Attempted to call a method for a module that is not installed natively (${moduleName}).`;
+    ERROR_MISSING_MODULE(namespace, nativeModule) {
+      const snippet = `firebase.${namespace}()`;
+      if (Platform.OS === 'ios') {
+        return `You attempted to use a firebase module that's not installed natively on your iOS project by calling ${snippet}.` +
+          '\r\n\r\nEnsure you have the required Firebase iOS SDK pod for this module included in your Podfile, in this instance ' +
+          `confirm you've added "pod '${NAMESPACE_PODS[namespace]}'" to your Podfile` +
+          '\r\n\r\nSee http://invertase.link/ios for full setup instructions.';
+      }
+
+      const fbSDKDep = `'com.google.firebase:firebase-${GRADLE_DEPS[namespace] || namespace}'`;
+      const rnFirebasePackage = `'io.invertase.firebase.${namespace}.${nativeModule}Package'`;
+      const newInstance = `'new ${nativeModule}Package()'`;
+      return `You attempted to use a firebase module that's not installed on your Android project by calling ${snippet}.` +
+        `\r\n\r\nEnsure you have:\r\n\r\n1) Installed the required Firebase Android SDK dependency ${fbSDKDep} in your 'android/app/build.gradle' ` +
+        `file.\r\n\r\n2) Imported the ${rnFirebasePackage} module in your 'MainApplication.java' file.\r\n\r\n3) Added the ` +
+        `${newInstance} line inside of the RN 'getPackages()' method list.` +
+        '\r\n\r\nSee http://invertase.link/android for full setup instructions.';
     },
 
     /**
diff --git a/lib/utils/ModuleBase.js b/lib/utils/ModuleBase.js
index 2cda6291..7e965dad 100644
--- a/lib/utils/ModuleBase.js
+++ b/lib/utils/ModuleBase.js
@@ -58,7 +58,12 @@ export default class ModuleBase {
     const nativeModule = NativeModules[this.constructor._NATIVE_MODULE];
 
     if (!nativeModule) {
-      throw new Error(INTERNALS.STRINGS.ERROR_MISSING_MODULE(this.constructor._NATIVE_MODULE));
+      throw new Error(
+        INTERNALS.STRINGS.ERROR_MISSING_MODULE(
+          this.constructor._NAMESPACE,
+          this.constructor._NATIVE_MODULE,
+        ),
+      );
     }
 
     // used by the modules that extend ModuleBase