Marriage is a compromise. It is about give and take. That means sometimes you may have to give in on some things. Decide which things are of prime importance and which are not worth worrying about.
Some things, like differences in faith and values are more likely to present serious challenges than character traits like untidiness or whatever it may be. Of course if the character trait is selfishness or anger that results very quickly and with consequences for those round them, then you might want to give it serious thought.
So before you go into it you need to consider whether you can live the faults of your intended spouse. By the way, if you’re not seeing any faults that in itself is a problem because it means you are looking at your intended through rose colored glasses and not realistically. But supposing you are already married and only now starting to see those problem areas show up? What then?
The best solution to problem areas in a relationship is to talk it over. Little things like squeezing the toothpaste from the top can be a constant source of irritation for some people. If something your spouse is doing something that is annoying you, then you need to decide if it is a major issue? Is it something you can live with or is it something that makes you angrier and angrier each time it happens?
If it is the second one, then you need to sit down calmly and explain to your spouse that you are finding this to be a problem and why. Don’t wait till it builds up and up and you explode. It is far better to tackle the issue when you are calm and not emotional. It is quite likely there is something that you are doing that is driving your spouse mad too, in which case maybe you could suggest a trade off. You will try harder to work on that problem if they will agree to work on theirs.