How do I stop making the stupidest mistakes?

[bobcat2819@yahoo.com]

I keep getting tambien and siempre mixed up. I keep getting este and ese mixed up. I keep saying things like, "un persona inteligente". I use ocupado imstead of preocupado or interesante instead of inteligente. I can't seem to stop making these simple mistakes. Ive tried slowing down and those things still keep happening. It is like I just dont see the little things. When they are wrong and when I correct them, they are in my head for that day but I do the same thing the next day.
I repeat them to myself while cleaning or driving. I still forget them and make mistakes like that constantly. I am about to give up. Does anyone have a hack for this?

[IceVajal]

I'm learning Russian and some words just don't want to stick. I have a letter size blackboard where I write down what I struggle to remember. That small blackboard is hanging in a prominent place, so that I see it several times every day. And after awhile I remember the words. But what works for me won't necessarily work for you!

[luo-ning]

I usually try constructing a sentence and drilling it several times (speaking it out loud) each time after I make the mistake, while thinking intensely about the meaning.

For example, when you notice yourself mixing up “ocupado” vs “preocupado”, you make up a sentence like “no estoy ocupado, pero estoy muy preocupado” and imagine yourself lying on a beach with a cocktail but unable to relax properly because you keep worrying you left the door unlocked.

Or for “este” vs “ese”, you could say “este árbol es chiquito, pero ese árbol es gigante” and you imagine standing next to “this” tiny bonsai tree, with “that” gigantic redwood tree a bit further away.

You'll probably still make the same mistakes, but when you do, you just repeat the process, maybe with a different sentence this time. And hopefully over time, you'll find the frequency of mistakes gradually reduces until they're either completely eliminated or so rare that they're no longer problematic. Remember that 100% accuracy isn't the goal — even native speakers still occasionally mix up words in their own speech.

[Cifi]

There are a few different things for me:

Mistakes I frequently make because my native language doesn't have that concept or works in a different way. Examples from English might be "verbs like gustar", the "personal a" or the need to adjust adjectives to match the noun.

My way to deal with these is to drill them in context until ¿usted gusta la ciudad?, veo el hombre or un persona start to feel just wrong.

Then there are some words I just keep mixing up. For me, this would have been e.g. verano and invierno for quite some time. I instantly knew they mean summer and winter, but had to think hard to know which is which. Another example would be gorro and gorra which are different things though they both may translate to cap.

With these, I try to find expressions that would allow me associate a picture to it, like "gorro de lana" vs "gorra de béisbol", or "casa de verano".

Then, there is an effect of making "silly" mistakes because of distraction/stress. Say I'm struggling to get verbs like gustar right, I might eventually use this correctly, but maybe use the wrong article where I normally wouldn't. Similarly, as long as speaking feels challenging (and it still does, though a lot less than it used to), I make more "silly" mistakes when talking.