Extras you NEED:
- Join an astro club and go to the observing sessions. The experienced members will be your best assets.
- Red torch - just some cellophane over a normal torch will get you going.
- Planisphere - the big Chandler one is great.
- Collimating equipment - either a cheshire eyepiece or a laser collimator. Either one will get you going.
- Stool - to allow comfy viewing.
Extras you may THINK you need:
- Better eyepieces - the ones that come with the scope will keep you going for quite a while till you learn to observe.
- A Telrad - now this is a toss up whether its an essential or nice to have.
- Filters - most filters people buy spend most of their time in the box and not on the scope. The only one that may be useful would be a variable moon filter to make observing the moon more comfy.
- Atlases - good sky maps can be found for free on the web for a while till you have time to look around.
I would say, so long as you can collimate it, find your way around the sky and are comfy then you will go a long way quickly. All the other accessories will come in time.
Cheers