I try to be lightweight but without spending huge amounts of money. I think that the site
www.outdoorlab.com is a good start and reference point, they have a section called ultralight. My rucksack is a 48L Osprey Exos, more than enough space for me. For sleeping I now think of it as a 'system,' so I have a groundsheet, then my choice is a tent or a bivi, my preference at the moment is a bivi, which is lighter than my tent. Then my mattress, the lightest and smallest one is a Thermarest Neo Air, which is best when I 'tent' a hike and a Thermarest Prolight which is best when I 'bivi' a hike. I use a down sleeping quilt, no back and no hood to it, compresses very small and is lightweight and am always very careful to not let it get wet.
My boots, the winter ones are Berghaus Superlights and the summer ones are Salomon Ultra X's, I'm happy with both.
When I'm hiking I try to work in twos, Two lightweight pairs of hiking trousers, both from Decathlon £7.99 each, perfect, comfortable and well made. I think they are £12.99 now? So easy to wash and dry. If I need warmth I just put on a pair of long johns, they also double up as sleeping wear.
I take and wear two pairs of Decathlon boxer underwear, £3.99 a pair, they are so so comfortable and super easy to wash and dry. I take and wear two long-sleeved synthetic baselayers and have just bought two Columbia Silver Ridge hiking shirts (£25.00 each) to compliment them. I haven't worn them yet. I then have a synthetic, not too thick, warm jacket from Alpkit and a full zip fleece Berghaus cardigan plus my most important top, my wind jacket. This year I've started to take my Rab Microlight jacket with me which I only wear first thing in the morning when I get out of my tent and when I'm settled for the evening, its one and only job is to keep me warm when I'm stationary.
I have a lightweight pair of Montane mittens and a £1.49 pair of gloves from Decathlon, they work well together. I also wear a wide-brimmed hat when it's hot but I also have a Lowe Alpine hat as well which keeps my ears warm.
For keeping dry I use a Champion long waterproof coat (£15 when I bought it) and a rain skirt, plus a pair of Rab Gaiters.
My routine with my clothes is to wear one and wash and dry one each day, all my routines are done when I camp for the evening, it works well for me.