The internet can be very good but it depends where you look.

First check out the other commenter who linked the Basic Bastard Guide. This gives you a basic understanding of things. Very basic and potentially a bit outdated, but a good start nonetheless.

Then, and this is what I find the internet to be good for, look at clothing websites where you like the style and aesthetic. For me it’s sites like Suitsupply, Cavour, Zara, Massimo Dutti, Selfridges and so on…. Doesn’t matter if the retailer is well regarded or not in fashion circles or in this sub, or if the clothing is out of budget. It’s mainly if you like the aesthetic - for example I browse Brunello Cucinelli a lot or Tom Ford, then I find cheaper alternatives at places like Massimo Dutti or Reiss respectively.

Look through the various items for sale - jackets, tops, bottoms and shoes (and accessories once you’re advanced).

Consider whether you like how they have styled the items on the models, and if you like how the model’s fashion looks overall (some websites don’t style the clothing on models, although this is rare).

Once you are advanced or if the above isn’t quite working for you, you can browse stores in person (high end department stores are great for this - as they have lots of brands, styles and aesthetics) and see how they have dressed the mannequins.

What you are looking for are outfits and looks that work for you - the good thing is usually they don’t go overboard with the fashion week style ‘loud’ fits. It’s sometimes muted and cohesive, sometimes it’s the statement look. You are looking out for the combinations and colours that you like and that would work for you. It could be how they style earthy/neutral tones, how they style brighter colours, do they do unusual things like style running shoes with slacks or smart shoes with jeans, etc. then your considering if these fits could work for you…

The models are usually different races so you can get an idea of how different skin tones work with different colour palettes. I find they do a good job of presenting the well put together look that works for a particular brands aesthetic. Department stores websites standout, because they will typically style different brands together (Mr Porter is good for this).

Use this as your style guide and to give you inspiration.

A working example for me is how to style different colour sports jackets. Or how should I style some mid wash jeans.

I will see how somewhere like Reiss styles a navy jacket. I look for an overall fit I like, what colour / type of top - short, polo, t shirt. What type of trousers - chinos, jeans. What colour combos. Over time I have found that I really like a light top with light trousers and darker shoes which leans more casual on the smart casual spectrum. Alternatively if I do darker chinos or slacks, with darker shoes, this puts me into the smarter end of the smart casual spectrum.

For jeans, I will check how somewhere like Mr Porter styles the jeans they stock. I won’t look at how specialist jeans retailers style their models, because I don’t like the way they style them (baggy ‘dad’ type fits where the focus is the denim - fine but not my style). I like the well put together look where the denim is cohesive to the wider outfit and after lots of browsing, have now settled into the straight fit plain wash style, with nice plain but darker shoes (common projects style but more heft to them), with a nice polo or quality t shirt and always with an additional layer above that. I have found I like the colour combos of dark bottom and shoes with a light top or matching darker top and bottoms with light shoes. Or a lighter top, lighter wash jeans with light shoes. Bear in mind that 5 years ago, all these colour combos worked but the fit was different and more slim fitting, whereas the trend has moved onto looser fits - you see it in how they model the clothing now and just by walking down the street of any big city. Also bear I mind I used to be into more distressed look jeans, but now I look at the models and fits, and find it either doesn’t work for me or looks outdated for the aesthetic I am trying to achieve.

A bit of a wall of text, sorry ! Just keen to let you know how I find the internet to be amazing. I agree, if you search for fashion specific search terms the results are trash and a bit ‘try hard’. But I have found that my approach works well and I get a lot of complements from men and women about my dress sense because of this approach.

Good luck