What things an entrepreneur should get copyrighted before approaching VCs

You are asking an extremely broad question, while giving us almost no information about your "online venture". The question as you pose it, is impossible to answer.

I will say this though. VC's invest in people, not ideas. If you have no hope of making the most of your idea, it will be stolen. Some way, some how. If you are the best person with the best team for the job, you are safe no matter what. That is your best protection.

What you are talking about it Intellectual Property protection (of which copyright is one strategy.)

You have several options:

1. You can apply for a patent. However if your business is growing quickly, this is not going to work for you as the patent process is quite long and you have to have not revealed the idea to anyone before a certain stage.
2. You can ask the VCs to sign an NDA - and they will say no.
3. You can develop some traction - ie. a customer base and some income which the VCs can't take. ie. Make the business an irrestible proposition and they are likely to invest in you rather than steal the idea.

The point is, that it is really difficult to protect an idea unless you control some kind of rare resource which is vital for the implementation of the business.