I do the same as Blinko.
Put out everything that 'might'go.
Stick to basic colours i.e. navy, pale grey, taupe, white.
Make sure that everything goes with everything else.
All trousers except linens are ankle grazers.
Then pop in a few odds in a bright colour like, for example, fuschia linen trousers, pink linen peg trousers. A pink scarf and a different shade pink pashmina.
Couple of maxi dresses, with sleeves, that will do day or evening.
Sun hat and sun glasses etc.
Let it all sit/hang for a day or two.
Then.... if there are two similar items decide which one, or maybe you want both. Do this with each item.
I try every item on and don't skip on this. Make sure I'm satisfied it looks ok, it fits ok, it is comfortable. If not, don't take it. I don't want anythng that is not earning its space in the suitcase. I want to be able to pick up any item and know without doubt that it is wearable.
Shoes...
Clarks velcro comfy walking sandals - 1 pair dark pink that go with everything, and 1 pair pale grey that go with everything.
Pair shiny pewter leather FitFlops which go with everything.
Later on if I have room I may add white lace up plimsolls and/or a pair of flat navy leather comfies.
Roll each item up and pack. I don't worry cos I will probably unpack and pack again at least once. Check everything fits into my case and weigh it. Luggage weighing scales are worth their weight in gold and I take them on holiday with me so I can check that my case is not overweight for the flight home.
Now, if I have space in my case and am under baggage allowance, I'll have a look and anything I might take 'just in case' but often I don't add anything. I still have to add toiletries etc.
It is quite liberating to know that I don't have masses of clothes with me, but do know that every item will work with most other items.
By this time the sweat is blinding me, I feel confused so close the door and go to bed. Next time I look at it is with a fresh mind, it has all fallen into place. When everything is spread out on the bed or hanging around the room there is nothing that is lonely, that doesn't have several friends.
It's worth taking time and it gets easier, I can do this so much more easily that the first time.