Definitely helps to have funds. Just because you are living simple doesn't mean you want to be stressed about where the money comes from. The times I did this without reliable income were harder.

Open-ended is harder than having a destination (or return home) in mind. If you have a plan for how the vagabonding comes to an end it is a little easier. One time, my wife and I lived out of our car for a few months while traveling around the US, but we didn't have a good idea of what we were going to do next. There was no place we were trying to end up. Eventually we just kinda settled down somewhere because we were tired of traveling. I think its better to plan to end somewhere or to have a conclusion in mind. Or a home to return to. Whatever that looks like for you.

You really don't need to pack much. If you aren't camping, couple pairs of clothes for everyone, a laptop or at least a smart phone is good enough. All the other stuff can be found along the way.

Give yourself a theme. This sounds silly, but traveling is always better when you have some focus. So pick something to give yourself a little purpose: (eg. Im going to take a picture of every train station in Provence, eat at one falafel place in every state on the US Atlantic coast, ride every city bus in Buenos Aires--it really doesn't matter, just pick something specific to give yourself some focus). There are a bunch of small mosaics in Paris hidden around town on the sides of buildings above street signs, and my kids and I walked all over the place trying to make a map of them. Got us into parts of town we never would have visited otherwise.

Don't worry if it all goes wrong. I've never been on a long trip that went as planned. Its okay to change your plans.