There was a thread here somewhere which contained a lot of advice regarding lightweight trekking, but I can't find it.
So, my suggestions regarding clothes were (assuming you aren't intending to dine with the Queen):
1. Take 2 technical T's and underwear. Wash the one you've been wearing when you stop for the night, and it should be dry by the morning.
2. 3 pairs of socks, because if you wash one pair they can take a couple of night's to dry out.
3. One pair of cut-off trekking trousers. Generally, the part of a pair of trousers that gets dirty is the lower leg, so if it's not too cold then you can unzip the lower, wash it and zip it back on when it's dry in the morning.
4. One fleece - if it's summer you're unlikely to need it until it gets cooler in the evening, so why take more than one?
5. I tend to use a lightweight waterproof in the summer which packs down to very little (mine's a Lowe Alpine Triplepoint at around 500 grams). If it does get cool and wet while you're walking, put the fleece on underneath.
Apart from that, I suggest you use the suggestions previously noted, i.e. examine everything you intend to take and consider whether it is required or just 'nice to have'. Most people also allow 1 luxury - mine's a book, but you might like an ipod or similar.
If you're cooking, do you need a full cookset? If possible I tend to take a pair of those aluminium pans and use them to eat from as well. Also, get a set of small plastic containers so that you only take as much of things as you need (e.g. sugar). If you use resealable gas cylinders you can also use them with a gas lamp after you've finished cooking. I only take a liquid fuel stove for high altitude trips so you wouldn't need that.
Washing - I assume you're using one of the trek towels? I'm a bloke so take shaving oil rather than any of the things that take up loads of space or - Soap - I make my own shampoo bars, which are just soap made with oils that are beneficial to the hair (e.g. castor oil, jojoba etc), but that doesn't preclude using them for all over washing.
Maps - I use the paper ones with the outer packaging removed, and a waterproof map case. The waterproof maps are nice, but weigh more.
Well there's a few things I found reduce the weight I carry, and hope they help.
S.