So far, most of my travels have been just my son and me. Parts count a little toward "solo travel" (it was up to me to figure it all out, plus I needed to be responsible for a little human), other parts don't (had another person around almost all the time, so the "lonely" stuff never applied). Last summer I did a solo 5 day road trip, and later this month I'm headed to Sweden and Finland by myself (first trip where I don't take my son).
I agree that providing someone with your itinerary is a smart idea, but as someone who completely winged 5 weeks in Europe, never knowing where we were staying until the night before, and purposely not getting data for my phone (would just take advantage of wifi when I was around it), well, it's not really advice I've followed, just because I didn't have an itinerary. My dad requested that I "email him every day". I told him no. One, I'm an adult and I don't contact him every day of normal life. Two, I might go days without access to wifi, and the day I don't email him it will cause him to freak out and that doesn't help anything. He got my flight details, and an email here and there throughout the trip.
I actually tried to look up some cooking classes for this next trip, but I've only found one baking class (I will try to go to it, but it's only offered once a week, and I can't find any price details on it. There was one cooking class, but the price was $850, so that's not happening (you can sign up to four people for the one price, but I don't have four people).
Overall, just do it. Do some research and get a few "must sees", then some "would be nice to see while I'm there". Give yourself some down days (or not, I guess it depends on how you travel).
Getting lost... Some of my best finds were when I was walking around, completely lost. Keep a relaxed attitude about it, and it just becomes an adventure (and hopefully you don't need to be somewhere at an exact time). If you can, get a local area map from your hotel/hostel/whatever with your hotel/hostel/whatever clearly marked (or, if no map available, at minimum, have the address of the hotel written on a piece of paper, in the local language). When I've tried to find my way back to my room, more than once I'd just approach someone who looked local, show them the map, and ask directions. Sometimes they'd be able to get me to something halfway there, and just let me know "when you get here, ask someone else for the rest". When I wanted to get somewhere on a bus, in a remote area, I would show the bus stop and address (or site name, again, in the local language) to the bus driver, and they'd stop at my stop, let me know I wanted to get off there, then point me in the general direction of what I wanted to get to.
Language barriers... When I would arrive in a new country, the first thing I would do is go to "information" and ask how to say "hello", "please", "thank you", and "Do you speak English" in the local language. I'd write it down phonetically so that I could check it again if needed. I found that no matter where I was, if I at least tried to great someone in their local language, they would automatically switch over to English for me (if they could, and the one or two times they couldn't, they grabbed someone for me who could). This time, I've also found a translator app that will work offline (by typing only, but that's more than I've had on past trips).
It's also good to look up some of the local "social rules". For example-- in France, always greet someone when you walk into a store, hotel, restaurant, etc. In other countries/cities, it's not considered rude to just let go of a door and not hold it for the next person. If you expect that, you'll be prepared not to let it hit you. Just little things like that.
So far, I've used booking.com for most of my rooms. I book with the combo of "cheap, well rated, near public transportation". I haven't had a bad experience yet. You can look for hostels, hotels, apartments, etc.