Note: This was originally in Day One but I moved it here so we could reference it elsewhere.
Pro tip #1: lots of these guys will advertise on several sites so you may see the same “tour” in several places. When you see the cheapest one REALLY check to make sure food and drinks at each place are included. I bet they aren’t for the super inexpensive one and its almost always better to go with the slightly-higher priced one and having the guide pick up the tab than nickel-and-diming about what to get, fumbling with change, everyone in the group not getting the same things, etc.
Pro tip #2: Get a small group. It is SO much nicer to have 4 or max 6 people on the tour. Anything larger and it takes too long, is way too irritating for food preferences, takes a zillion years for everyone to settle up, etc. You may also miss out on certain tiny places that simply cannot handle anything more than a few people, which is a real potential issue in places like Japan. Do yourself a favour and ask the question before you book, it will be worth it.
Pro tip #3: Get someone who speaks both languages well. This might seem obvious, but it makes a big difference. We’ve had native language speakers who spoke some English (which was fine, especially with the amount of beer we drank anyway), a native English speaker who learned the native language years ago when they moved there (also fine), one native speaker and had 3 other languages, English being the very dead-last (not fine) and one fellow who spoke something like 6 different languages, all of them flawlessly (REALLY fine).
Pro tip #4: Make sure you understand the meeting point. Because here’s the thing….of your guide is a local, they look like everyone else and you will have anxiety that you’ve missed something or they won’t show up. So when you book online, make sure you understand. And make yourself visible when you get there. Most guides we’ve ever had could pick out the lost glazed-eye tourists at 300-paces, but it can’t hurt.