I would like to offer a contrary opinion without disrespect to the experienced senior members who have already contributed to this thread .
I think when it comes to dressing its way more important to "NOT Stand out in a bad way" than it is to dress extremely well and trying to stand out in a good way.
I know that
@Aussiedude is doing daytime approaching. Especially in daygame the whole concept is built around spontaneity and the narrative is " I was just going about my day and I saw you and I wanted to come meet you"
Now what do people do in the day? They are running errands, shopping for grocceries, going to and from work, going to and from the gym etc.
And as long as you are dressed "normally" and dont look like a homeless guy, you are going to be just fine. You don't NEED to be dressed extremely well.
Its not your fashion that has a major impact on how the girl reacts, its your confidence, authoritative demeanour in which you approach that makes the big difference.
If you think you need to be "dressed extremely well" then you are not going to be confident unless you are dressed extremely well! And if you are not confident, your approaches go worse.
The girls are reacting to your confidence, assuredness and the behavioral cues you are emanating. If you anchor your confidence to dressing well, you are building your confidence on a weak foundation.
This is when guys cannot approach confidently unless they FEEL they are dressed well.
So what happens if you have just finished your workout and sweaty and come out of the gym and see a hottie who is dressed up? You dont approach!
What happens if you go to a party where everyone is dressed to the nines and you dont "stand out"?
What happens if you go out and someone spills a coffee or drink on you and now you have a stain on your shirt??
Like seriously, you worked years on your confidence and a stain on your shirt can erase all your "confidence"?
That is what happens when you anchor your confidence to being dressed extremely well.
I have approached girls in everything from slacks, sweatpants, jeans, trackpants etc and gotten results. You can dress me in any clothes you want, and I will still get results.
What matters way more consistently is your eye contact, body language, vocal tonality, frame control etc in short CONFIDENCE.
Put me in any clothes that you consider is outdated or "not good enough" and I will still approach girls confidently.
Does dressing well, help? Yes but ONLY if it makes you act more confidently. If not, it hardly has any impact.
I would put my money on an experienced PUA dressed like a homeless guy getting way better results than a newbie dressed "extremely well".
All I am saying is there are consequences to anchoring your confidence to "your wardrobe or being dressed well".
But if you feel that you don't mind those consequences and having a shaky foundation to your confidence, then sure go ahead and try to always be dressed extremely well!
Consumerism rides on that. They will love you.

And it keeps our economies going.
If you dress okay, then my honest advice is forget the wardrobe and focus on getting confident, by doing tons of approaches and concentrating on your body language, vocal tonality, assuredness, assertiveness, frame control etc.