How do you find your first Advertisers?

I am hoping to launch an updated version of my site, Eurotriprs.com, this week and since I do not have my anticipated User Profile and pay walled features completed, I will do not anticipate many user sign ups for the paid version.

What I'd like to do is cold-contact advertisers for on-site advertising and advertising for a Podcast I am starting in January.

I understand a site/podcast with zero traffic has almost as much chance of getting paid advertisers, but I need to start thinking about monetization channels now.

How have others identified viable prospects for contacting to solicit advertising on your site? I have no problem cold-calling, cold-emailing, etc, but I am wondering how you put together a list of the initial advertisers you have contacted when you started your own native ad campaigns.

I know LARGE companies that would fit my niche (European Travel), but I am wondering how one finds a larger pool of smaller companies. To me sales (in this case advertising sales) is a numbers game, and the larger my list of prospects, the more likely I am to close a number of advertisers to ensure my required MRR. "100 calls -> 1 sale" So I need a list of several hundred prospects, but not sure an easy-ish way to find several hundred potential companies targeting European travelers.

I'm thinking: Guidebook companies, Hostels, Hotels, Airlines, restaurants, tour companies, tour guides, local attractions/sites, etc.

Any thoughts on an easy-ish way to compile such a list?