Finish README.

README.MD

@@ -6,10 +6,45 @@ a more expressive and compatible way.
 More information about each feature offered can be found at the [Wiki](https://github.com/LlamaLad7/MixinExtras/wiki).
 
 ## Setup
-For the time being, I recommend depending on this library via [JitPack](https://jitpack.io/).
-After adding its repository to your build script, you can depend on it like so 
+
+For the time being, I recommend depending on this library via [JitPack](https://jitpack.io/). After adding its
+repository to your build script, you can depend on it like so
+
 ```gradle
 dependencies {
     implementation("com.github.LlamaLad7:MixinExtras:0.0.1")
+    annotationProcessor("com.github.LlamaLad7:MixinExtras:0.0.1")
 }
-```
+```
+
+It is essential that you register MixinExtras as an annotation processor if you want remapping of custom features to
+work. If you are registering Mixin as an annotation processor too, ***you must register the MixinExtras annotation
+processor before the Mixin one.***
+
+### Bundling MixinExtras
+
+If you intend to use this library in your mod, you will probably need to bundle it in your jar.
+
+If you are on Fabric, I recommend using the `include` configuration in your `dependencies` block.
+
+If you are on another platform, I recommend the [Shadow Gradle Plugin](https://imperceptiblethoughts.com/shadow/). I
+also highly recommend you [relocate](https://imperceptiblethoughts.com/shadow/configuration/relocation/) MixinExtras to
+avoid conflicts with different versions of the library.
+
+## Initialization
+
+The final step after setting up your build script is to initialize MixinExtras. To do this, simply call
+
+```java
+MixinExtrasBootstrap.init();
+```
+
+somewhere suitably early in your program. On Fabric, this would be a `PreLaunch` entrypoint. If you cannot find a
+suitable place for your platform, you might like to use
+an [IMixinConfigPlugin](https://github.com/SpongePowered/Mixin/blob/master/src/main/java/org/spongepowered/asm/mixin/extensibility/IMixinConfigPlugin.java)
+. Initializing MixinExtras in your plugin's `onLoad` method should work fine on any platform.
+
+### You're good to go!
+
+Enjoy using the library, and don't hesitate to open an [issue](https://github.com/LlamaLad7/MixinExtras/issues) if you
+have any feedback, questions or suggestions.