safety for traveling alone

This is going to be really long, but I've been doing a lot of research and I wanted to write up a detailed answer that hopefully covers many different aspects for travelers.
If you’re traveling alone, Croatia would be one of the top recommended destinations for safety, smoothness, and of course enjoyability! Before even going into every feature, the one thing that first and foremost makes this trip smooth is the multilingual capabilities of the populace. Besides Croatian, many people speak English and often another language such as German.
Safety
Crime:
Unlike some other places, violent crime in Croatia is almost nonexistent, and your biggest day to day worry might be petty theft. However, doing the usual diligence of avoiding dark alleys, locking doors, and keeping your valuables next to you would be a good idea. Based on 3 years of user experiences on Numbeo.com, the Croatia safety rates of walking alone at night were 77% and during the day 90% (by comparison NYC is 50% at night and 72% during the day).
Traveler Registration:
Upon checking into your hotel/airbnb, you should expect that the hosts will take a copy of your passport as they are required to register all travelers in a database with the local police.
Natural Environment:
Another thing to consider for safety is the natural environment. Croatia tends to experience earthquakes, which have some damaged older buildings. So if you see a building that looks to be under repair or looks like a chunk has been taken out of it, best steer clear, as falling stones can happen.
https://www.total-croatia-news.com/news/49278-earthquakes-and-building-statics
Depending on how much outdoor activity you do, it would be best to consult with any kind of local park ranger or tour guide before venturing into the wilderness, as Croatia does have a few dangerous species of animals. Of course if you book something guided, they would know how to avoid this.
https://experiencedalmatia.com/top-ten-most-dangerous-animals-in-croatia/
And of course, like the rest of Europe, you can expect tiny, steep, and winding roads, sometimes without guard-rail, but are maintained in excellent condition. However, you may want to consider the terrain when walking anywhere, as many places are built on hills.
Medical Emergency:
In the unfortunate event that you will need to access a doctor during your trip, the US Embassy provides a list of English-speaking doctors on their site.
https://hr.usembassy.gov/u-s-citizen-services/local-resources-of-u-s-citizens/doctors/
Getting Around
Intercity - Air Travel:
Going between cities is very easy in Croatia, as the entire land mass itself is just over 21k sq miles. There are several options depending on your route and preference.
Croatia Airlines offers very low-cost flights between cities and they all take an hour or less, if you need to save time. They sell through their website (https://www.croatiaairlines.com/hr/) and through third-party sites such as Expedia.
Intercity - Train and Bus:
Trains do connect most cities in Croatia, which can be found at:
https://www.eurail.com/en/get-inspired/top-destinations/croatia-train
However, it is important to note that they do not connect to ALL major cities, including Dubrovnik, which is when the bus will come in handy. I personally recommend the Flixbus for this type of travel. It was timely, smooth and very inexpensive. When traveling from Split to Zagreb, I reserved a seat on the top deck, front row to get a panoramic view of the entire trip. This was great because the landscape of the main route from the coast to the inland is gorgeous!
https://www.flixbus.com/bus/croatia
Ferry to Islands:
While some of the islands in Croatia are accessible by bridge (such as Krk, Murter, and Pag), some require travel by boat. The ferry ports are located in the coastal cities and can take you to the smaller islands. There are several ferry companies you will find at the ports but it's best to reserve your ticket online beforehand. Here are some sites you can consult:
https://www.croatiaferries.com/ferry-timetables.htm
https://www.jadrolinija.hr/en/ferry-croatia
If you are using Google Maps to plan the route, you’ll find the ferry routes are drawn from port-to-port. The photo below shows an example of this connecting Split to the different islands (Hvar, Brač, etc). The dotted blue line charts the nautical route.

Metro Commuting:
Croatia has old charm, but is very modern, so you will find Uber everywhere metropolitan. Cities also have their own public transit systems. You would need to look into each cities bus/tram schedule, but also when you Google directions and use the public transit icon, you can usually find each stop along the way. In Zagreb the main website of the bus system is https://www.zet.hr/en. Tickets can be purchased from Kiosks/newsstands, which can be seen along the main streets and in shopping areas.
Last Tips
Holidays:
Croatia has a lot of bank holidays, so make sure to know when those are, because things will definitely be closed, including many grocery stores.
https://www.officeholidays.com/countries/croatia/2022
Cash:
Almost every establishment accepts credit cards, but keep some cash (Croatian Kuna) because a handful of the smaller cafes, restaurants, and shops will only accept cash.
Summer Travel:
June-August is a popular time for people within Croatia and foreigners to flock to the beautiful Adriatic coast. Prices will be higher and crowds deeper during this time. Exploring inland such as Zagreb will be quieter, but also some places will be closed because people are on vacation.
Mosquitos:
When it’s warm, there can be A LOT of them. Go to the Ljekarna or Farmacia and get repellent if you want to be outdoors at this time.

> Being a 67 yr. old female, is this a safe country to tour on your own which I am used to anyway?
I'm in a similar age group and used to travelling alone. Imo, Croatia is no more or less safe than any of the other 27 EU (European Union) countries. To be frank, I feel much safer in all EU countries than I do in US cities and I certainly wouldn't think twice about visiting Croatia alone (and I didn't!).
The main potential problem, as everywhere in Europe, is pickpocketing rather than anything more serious such as mugging or assault. So just use normal travel commonsense. Keep your valuables in the hotel safe, keep most cash & cards safely underneath your clothing, use a bag with a cross-body strap. don't wear expensive jewellery, don't flash cash, stay alert and notice who's nearby when using ATMs, avoid dimly-lit and deserted places after dark, guard your drink, don't accept lifts from strangers etc etc
> since it's not like Europe where you can get around on a train, 
Croatia has a railway network which is safe to use and has fares which are very reasonable indeed. The official site for timetables and fares is Hrvatske Željeznice Putnički Prijevoz but you can also find train times & details in English on the official German railway website https://www.bahn.com/en
Trains generally run to and from Zagreb, the capital. You can, for example, get a train from Zagreb to Split or Rijeka (with intermediate stops, obviously).
There is also an extensive network of long-distance and local buses. Again, these are safe to use and prices are very reasonable. You can find a list of Croatian bus operators linked on this page:
https://www.visit-croatia.co.uk/travelling-around-croatia/bus-travel-in-croatia/
>these are more like islands you have to get to
Croatia isn't really 'more like islands'. The mainland part of the country is huge, beautiful, full of history and culture and well worth exploring. The many small islands along the coastline are served by a network of ferry routes. You can see routes and find info about timetables etc on this site:
https://www.croatiaferries.com/maps/
The vast majority of younger Croatians speak at least some English and many are fluent. In normal times Croatia has almost 2 million tourists (with most coming from the other EU countries) and you'll find plenty of English spoken anywhere which is visitor-popular e.g. Zagreb, Split, Rijeka, Dubrovnik City Walls Pula, Zadarand islands such as Hvar, Brac, Korčula, Krk
Enjoy your planning!