I experienced the same thing with paradox of choice. Unfortunately the solution was just to spend a lot of time on it, trying different things and researching options by asking people and doing internet searches and browsing malls and outlets. Going from "no good clothes" to "all good clothes" took me a full year of off-and-on effort.
Most important thing is finding things that fit. I didn't used to know what this looks like, but by trial and error and feedback from others I learned. Personally I aim for things that fit snugly without being too tight. I think a good mental rule of thumb (at least as a straight man) is to think about what looks attractive on a woman-- things that tastefully emphasize her figure. I realized the same goes for men. You want clothes that show your body's lines. This means jeans that aren't baggy, but which show off your legs and gluts. It means shirts that bring out your chest and shoulders or which simply mesh with the lines of your figure.
A really important thing is feedback. Women friends are best for this because usually they're much more aware of style than men are (just how it is). DO NOT ask parents or older relatives; do not ask male friends unless they have notably good style. In general you want feedback from women who you know well enough to trust them to be honest with you.
The /r/malefashionadvice subreddit can be very useful, it's a mine of recommendations, discussions, and guides.
Lastly, a general outline of what I went with, just to give starting ideas:
-I wanted a collection of well-fitting t-shirts. I ended up mostly going with v-necks from Uniqlo, personally-- they're cheap but fit me well. There's a million options for simple t-shirts, from Target to Banana Republic to Tom Ford. Frankly you can go cheap here and be fine.
-I wanted an assortment of well-fitting jeans. I ended up with Everlane, tailored Levis, and Diesel, in different shades of blue and black. I'm still looking for chino pants that work for me.
-I wanted a wide array of button-up shirts. This is important because it's just the cornerstone of modern male fashion. Nothing gets noticed faster than when someone switches to wearing these, imo. I get these from all over: Macy's, Banana Republic, Express, Armani Exchange, Club Monaco, and Levis. Make sure they're not baggy! Wear them over a t-shirt and roll your sleeves up, it's a great look. Leave the top two buttons open.
-I wanted a wide array of shoes. I literally wore white New Balance sneakers for 27 years until moving to NYC and being shamed into diversifying. I found that boots come in many varieties and look fantastic with jeans. I have a pair of Timberlands, some cheap black leather Polar Fox ones from amazon, some suede Steve Madden boots (cadwyn), and some Rockport tennis shoes.
I also got some sweaters and better-fitting sweatshirts. I'm still working on finding a winter coat that looks nice. Scarves are great!
Apparently you live in London, so you're in one of the best places in the world to buy clothing (along with NYC and Paris). You can find anything there.
All in all I think I've spent around $2500 on the full wardrobe, but you could get away with less.
Asking for feedback is crucial. Before I did that, I performed many iterations of buying some items I think look good on me, wearing them a few times, and getting rid of the ones that don't get any compliments (most of them).
A TL;DR of OPs post: start simple. Visit /r/malefashionadvise and follow the basic starter guide, i.e. chinos, white oxford shirt, and leather shoes.
You DO NOT need to spend 2.5k to look good: aim for 100-200 from ASOS.com and you'll look fabulous! You can order multiple sizes of the same product and return those that don't fit. Fit is key!
Check eBay for good quality shoes if cost is an issue (e.g. Meermin, etc) as imho that's generally the large cost in the wardrobe.
I experienced the same thing with paradox of choice. Unfortunately the solution was just to spend a lot of time on it, trying different things and researching options by asking people and doing internet searches and browsing malls and outlets. Going from "no good clothes" to "all good clothes" took me a full year of off-and-on effort.
Most important thing is finding things that fit. I didn't used to know what this looks like, but by trial and error and feedback from others I learned. Personally I aim for things that fit snugly without being too tight. I think a good mental rule of thumb (at least as a straight man) is to think about what looks attractive on a woman-- things that tastefully emphasize her figure. I realized the same goes for men. You want clothes that show your body's lines. This means jeans that aren't baggy, but which show off your legs and gluts. It means shirts that bring out your chest and shoulders or which simply mesh with the lines of your figure.
A really important thing is feedback. Women friends are best for this because usually they're much more aware of style than men are (just how it is). DO NOT ask parents or older relatives; do not ask male friends unless they have notably good style. In general you want feedback from women who you know well enough to trust them to be honest with you.
The /r/malefashionadvice subreddit can be very useful, it's a mine of recommendations, discussions, and guides.
Lastly, a general outline of what I went with, just to give starting ideas:
-I wanted a collection of well-fitting t-shirts. I ended up mostly going with v-necks from Uniqlo, personally-- they're cheap but fit me well. There's a million options for simple t-shirts, from Target to Banana Republic to Tom Ford. Frankly you can go cheap here and be fine.
-I wanted an assortment of well-fitting jeans. I ended up with Everlane, tailored Levis, and Diesel, in different shades of blue and black. I'm still looking for chino pants that work for me.
-I wanted a wide array of button-up shirts. This is important because it's just the cornerstone of modern male fashion. Nothing gets noticed faster than when someone switches to wearing these, imo. I get these from all over: Macy's, Banana Republic, Express, Armani Exchange, Club Monaco, and Levis. Make sure they're not baggy! Wear them over a t-shirt and roll your sleeves up, it's a great look. Leave the top two buttons open.
-I wanted a wide array of shoes. I literally wore white New Balance sneakers for 27 years until moving to NYC and being shamed into diversifying. I found that boots come in many varieties and look fantastic with jeans. I have a pair of Timberlands, some cheap black leather Polar Fox ones from amazon, some suede Steve Madden boots (cadwyn), and some Rockport tennis shoes.
I also got some sweaters and better-fitting sweatshirts. I'm still working on finding a winter coat that looks nice. Scarves are great!
Apparently you live in London, so you're in one of the best places in the world to buy clothing (along with NYC and Paris). You can find anything there.
All in all I think I've spent around $2500 on the full wardrobe, but you could get away with less.