Unless you're meaning actual mods, in which case, interesting, no idea?... if you simply meant plugins, which are what most people use, I consider the basics WorldGuard, WorldEdit and Essentials, plus a permissions plugin (PermissionsEx or GroupManager) and in my case CommandSpy that makes some functions simply easier for top staff.

Without more specifics, -Don't release your server before you're done unless you like shooting yourself in the foot, -Just downloading plugins, making a simple spawn and releasing the server will get your server in a dead place quickly, and -No server that's worth a damn comes without work. If you don't want to invest time, effort and (if you want any sort of decent hosting) money, you shouldn't own a server.

Oh, and don't recruit a dozen staff before you release. An owner can outdo dozens of the goofballs on this site that call themselves "admins", "developers" and everything else. Good owners can set stuff up themselves. And a survival server is the simplest procedure of them all (though perhaps not completely easy if you're looking to do it right).

And if you're only hosting a server to own a server, you're just contributing to the oversaturation and the server probably won't go anywhere. If you're hosting to give the community something good, you might have a chance. But that leads to the last point:

Don't expect donations, don't expect success. You might have a short hard place and spike up. Or you'll just die like most survival servers do.

Sorry to be blunt, I don't sugarcoat.