I have looked in charity shops and I struggle to find things worth buying (as a 40ish year old man). I tend to find the men's stuff is either the kind of stuff my grandad would wear, or it's the cheap Primark tat being sold for not much less than it can be bought for new in Primark.
For clothing, you need things to be in stock, in a size that fits, in good condition and with a colour that you like.
I like Rohan clothes. They have a range of styles, some of which look like you have just stepped off a mountain, but others that are
They use hard wearing fabrics, which are machine washable, very fast to dry, and don't need ironing. They are great for traveling, as you can hand wash them, roll them in a towel and hang it up, and it will be dry in a few hours. They have plenty of pockets, some of which are zipped.
The downside is that they can be expensive.
Once I have found something that I like, then I'll set up an eBay search for it, for the specific size, and style that I want, with a price filter. Then I'll get an email when something matches, so I can get a shirt for £20 which would have been 3 times as much when new. It means I can get exactly the same size and style to the ones that I've already got, even if they are a few years old. If you go to the Rohan shops, then the styles and fit change from time to time.