What kind of language?
The first thing you want to notice is the kind of language your reader will use. It is often not the language you would use. You want to identify and list how your reader will name things and what exact sentences they will use to ask for them.
The words and key expressions your reader will use when they speak
In your list of questions, you can start to regroup the words your clients use most often.
They will be looking for a "clean guesthouse or hotel in your town near the train station", and maybe they won't be asking for a "budget accommodation a reasonable distance from transportation". This is the type of misunderstanding between website readers and builders that happens surprisingly often.
You want to identify the expressions your visitor will use and recognize most easily.
Note that Keywords don't have the same importance. Often the location is crucial. Readers won't search for "great Japanese restaurant", they will however look for "Japanese restaurant in New York". The web is vast, if you are a location based business, mentioning where you are is not only important it is essential.
Your own keywords
You also want to list the specific more exceptional language that your business is presenting. You want to talk about what makes you different and special. In terms of marketing you could call this a niche.
For example the things that a traveler finds in a guesthouse that would make him want to come back, such as live jazz, cooking classes at the guesthouse, specialty deserts or even something simple like a mountain view are also the things that people will be searching the web for.
The expressions your visitors will likely use on search engines
The way a person asks for information when he talks, or when he reads a website and when he asks a question on Google are often very different. It is your job to know the language that your client will use in each of these cases and adapt your website to it.
The usual mistake
Of course, there is always the temptation to put in your titles of your site and in your pages only what you think Google "likes". But you need to be very careful that your readers are also able to understand and feel that you are talking to them. It is better to explain things to your readers rather than trying to feed the search engines.
Also, repeating the same things over and over will not help your site on Google but it will really hinder the way your readers experience your site. Google also will try to detect if there is an abnormal density of keywords.