Opening an LLC corporation in Delaware?

Hi, I work for a real estate agency in Spain and in order to deal with American banks we need to open up an office in Delaware. I got all the information on incorporating, but I was hoping that somebody who has done this before could give me a few pointers. Apart from the Certificate of Formation of a Limited Liability Company form, I was wondering what else I would have to fill out and send. Any advice on this would be greatly appreciated as most of the places that deal with this on the internet are always trying to sell something. Thanks.