Strategy for selling a house - what is the best way to proceed?

Account balance at the move-out is not bad, but the person could have borrowed it temporarily and by the notary appointment it’s gone again and the financing has fallen through.
In principle, only a bank guarantee is absolutely secure, but hardly anyone will be able to get that for you beforehand. If they do, then this is your candidate.

I’m telling you, you’ll end up at 650,000...
You can try your idea of asking the interested parties if they want to know. Or you demand some sort of application and give it to the most likeable ones who can plausibly secure the financing?
Or maybe even the least likeable? After all, they have to endure your neighbor(s).

Or maybe even the most unpleasant? After all, they have to put up with your neighbor(s).

Heavy Metal starts at 120 decibels \m/

and you forgive the nicest, ... Or maybe even the least likeable?

that probably depends on how good or bad the neighborhood was?

I have now followed your advice. Since we are not quite finished with the photos yet (it should also look a bit nice), I have actually put it in the newspaper as a code for now, first without a photo, without a price, just described. And then we'll see if/who responds. I will then tell the people with serious interest that I want a 5 at the front of the price (I can also justify that solidly). And if I have several serious interested parties, I will ask each of them to propose a price they would like to pay. And with equivalent creditworthiness, I would then offer it to the highest bidder,

I have lost track. Did you mention a price or not?

What you are doing now is quite simple. Schedule appointments in roughly 45-minute intervals, then the others will inevitably see that there are several other applicants, because then you will run into each other between appointments. Aside from that, it is probably clear to everyone these days that with such a (beautiful) house, they will not be the only interested party. Ideally, you will already have a few confirmations at the house in the evening or the following day. If there is only one and you have a good gut feeling about them, you will probably try it with them. If there are several, I would also go by gut feeling first and agree to the most likable people with whom you can most imagine that it will also fit financially and who will go through the whole thing with you. To the others I would say: sorry, someone was faster than you at first, but NOTHING is finalized yet. That way you don’t immediately scare off the others, since there are currently not many such great new houses at this price in your area. Now if someone comes along and then offers more AND you can imagine that they will take it, then you are of course suddenly in a bidding process (that’s why we said you should ask for more right away). I personally wouldn’t be up for that, because it can also backfire (= you scare off the best applicants). However, I can also understand that you don’t want to say no to that, I would have also looked at the house at >539. Ultimately, the "fear" remains until the ink is dry at the notary. Whether the chosen ones stick around, no one here can tell you.

So far, everything that the vast majority here said has come true. All your "I can't imagine" and "I don't believe" regarding paid prices, demand, etc. have been disproven. You could, based on how you describe the statements of the interested parties, easily ask for over 600k. So just do it, or do you have something to give away?