Let's start with the "bad experiences" part of your question: This might be trivial for some, but: Never ever pay any money before you've physically seen the apartment. There are quite a few rent scammers who will give you all sorts of excuses for why you need to pay before you've seen the place - don't be fooled.
Now for some meta-advice:
Ask a Dutch friend to come-with: The locals always spot things that foreigners don't.
Don't sign anything on the spot if you can help it: If necessary, make an excuse about having to get approval from somewhere/someone, or something else which takes the pressure off of you.
Compare your contract with other people's, especially other neighbors in your building if you can manage it, other tenants of the same landlord, or the previous tenant in your own apartment. (But don't make the landlord think you're snooping around too much.)
There's an official (?) document of conditions which apply to all rental contract and follow from Dutch law, that has been translated into English. Read it. You don't need to insist to insert all of that into your actual contract, but you should make sure you're not agreeing to anything contrary to it - and that the landlord is passing off something he's required to do anyway as some sort of a great favor.
Ask the landlord about an estimate of the energy cost for the apartment over the past year or so; specifically, ask if there is anything which causes excessive costs. That's essentially "fishing", but it's harder to lie about this than it is to just fail to mention it.
Ask whether any recent rennovation of repair work has been done in the apartment over the past several years.
If something was done, ask about the cause and what was fixed.
If nothing was done, perhaps it's time to do some work on something (which you have previously thought of)
Speaking of repair work - the way the apartment is right now is not entirely set in stone. It is not unacceptable to list issues that bother you and ask for them to be addressed; of course - there's a trade-off between the landlord wanting you to sign the contract and not wanting someone who'll nag him a lot.
A tricky point which is not yet clear to me is, what kind of expenses is the landlord supposed to go to in fixing things, and how much are you supposed to chip in for things which naturally wear out or fail, due to regular daily use. Like changing worn-out carpeting, dust bins with a broken mechanism. or specialty lightbulbs.
It is somehow customary in many places in the Netherlands to have you, the tenant, install your own floorboards. Yes, you heard me right. That is i-n-s-a-n-e, utterly and completely - but it's a collective insanity, it's not just your individual landlord.
That is a quite subjective question, so here is my the quite subjective answer.
I would look to:
Price including agent fees and deposit
Neighbourhood: infrastructure, criminal situation, recreation areas or points of interest
Time travel to workplace
Owner's common sense and openness: I would discuss possible scenarios like broken washing machine, required balcony chairs, problems with hitting
Facilities in building and furniture in the apartment: is it fresh or recently re-decorated, how good isolated, double glassed, check mould in corners and bathroom
Read contract: what are termination conditions, what are rent increase conditions, what are procedure for deposit return
However, with the current situation on the rent market in Amsterdam and neighbourhood, I should much my criteria and make decisions super fast. I should also trust a lot my intuition since in such short amount of time brain can not make proper conclusions.
If you have free money I would advise to go with an agent who will help you with finding, he will save your time, he will check your required conditions and can speak landlord or his agent language.