Old Site URLs

So I had my site active many months ago and then took it down, I have recently decided to put it back up and start over.

With that said, there are a ton of urls in google that point to my site, however, using the wrong urls...what should I do? Just not worry about it and let the new urls start hitting google or is there a better way?

Thanks!

What are the old urls? an old domain? threads that do not exist?

A custom 404-page is the way to go for threads. It's easy to set up:
Create a Custom vBulletin "404 Page Not Found" Page, and direct vBSEO to use it.

Same domain, just links to threads that do not exist anymore.

I was going to setup a 404, just have not done that yet, I just was not sure if there was a better way.

That's the best way.

If you also install my logger product, you can see which referring urls are giving you traffic, and if you create a new resource, you can set up a custom redirect from that link to the new resource.

Advanced 404 Tracking Mod/Add-on