It's easiest if you have a way to tell when a lead has been generated, ie an online form, since presumably they are not booking directly on your site. Make sure when visitors complete the form (keep it short) that you send them to a Thank You page. You can set up Google Analytics to track when someone reaches the Thank You page (ie. those who completed the form). The same is true of Facebook. It's also best if you offer some kind of reward if they fill out the form, like some free highly desired information. The info can be anything from a vacation preparedness checklist to a best vacation spots guide.
When advertising using PPC, don't just throw a bunch of keywords into an ad group and hit "GO." Keep your ad groups tightly focused, and your campaigns very specific. It's better to have a ton of laser focused campaigns, each with hordes of tightly focused ad groups. As an example, a vacation to the playground might look like this:
Campaign: Swing lovers toddlers
Ad Group 1: swing vacation with toddlers
Keywords: [swing vacation with toddlers], "swing vacation with toddlers"
Ad Group 2: Baby swing vacations
Keywords: [Baby swing vacations], "baby swing vacations"
Campaign 2: Slides
Ad Group 1: Big slides
Keywords: [big slides], "big slides"
Ad Group 1: Big slides vacation
Keywords: [big slides vacation], "big slides vacation"
Ad Group 2: Big slides vacations
Keywords: [big slides vacations], "big slides vacations"
The reason for doing it this way is so you can figure out exactly what is working and what isn't. "Vacation" and "Vacations" are not the same keyword, and people may type them for entirely different reasons. One might convert, while the other could be a dud. The goal is to find the winners and pump them, while modifying or killing the losers because they waste money. Also, Exact Match  and Phrase Match"" convert very differently as well. Different keywords perform differently.
You should also be split-testing different ads that are specific to each campaign. That's another rabbit hole.
It's helpful to use the Adwords Editor tool because creating all those campaigns and ad groups is a lot of work. Copy/paste and spread sheets can be your friends.
Adwords is a pretty steep learning curve, so you'll need to dedicate a good bit of time to learning it if you want to get good at it. There are a bazillion things you can do with it, and like with a box of crayons, you can create impressive art or commit atrocities, depending on your skills.