Not wearing a Gore-tex or any other waterproof layer until you have to.
Starting out on my re-birth as an ex couch potato I bought a Berghaus Boulder Goretex coat, Edinburgh Woolen Mills supa dupa chunky fleece, another thinner fleece as a base layer, nice cotton T-shirts, good thick jeans, Long Johns, Skiing gloves, thickest Thinsulate hat there was....list goes on.
Utter misery !!....you could have cultivated skunk in my outfit without hydroponics.
I always wore (most) of it...
a/ because I'd paid for it... b/ seemed to be an 'outdoors' way to look.
T-shirts ran out one day and I bought some Craghopper Atoll's - couldn't believe the difference from cotton.....I'm on the road to recovery...
I'd read in forums like this about 'technical' clothing and Paramo, Event, Pertex.....all seemed like highbrow, high priced, toys-for-boys extravagance.
Now I've realised that walking is as important to me as photography, boozing, smoking & computer gaming I spend a corresponding amount on ensuring that I'm really comfortable when doing it.
I've found what works for me which is Paramo, I walk and birdwatch - no scrambling madness for me.
Summertime is usually a Cambia T-shirt, Fuera trousers & Smock (in case of shower) plus Keen sandals.....no weight at all.
Autumn & winter Cascada trousers, Cambia long sleeve T, Explorer top or Hoodie, either Cascada coat or Torres insulated smock.
I rarely have much clothing on - enough to feel comfortable with a spare T & windshirt in the sack.
Not being totally loyal I always carry a Montane Lightspeed just in case.
Some long dead relative always said to me "buy the best you can afford (once)" goes totally against the grain but does beat buying crap (many times).