Just wear what you feel comfortable in! Just be you. The other consideration is the weather as we are, typically, outdoors. Just like a wedding day if you have your hair done and mother nature is blowing a hooley then there's not much we can do but embrace it! If you want to climb about then we need the right footwear, too. You can bring a second pair that I can carry for you. If you bring an umbrella than make sure it's one you are happy to have in shot. So maybe a white or transparent on with a nice design.