This is the question I get most, and the honest answer is that it matters less than people fear — but a few things genuinely help.
Colour: go softer than you think
The hill country is overwhelmingly green, and green is a difficult background. Cream, warm white, dusty pink, soft blue and earth tones all sit against it beautifully. Bright saturated colours fight it, and pure black loses all its shape in shade.
If the two of you coordinate rather than match, it reads better. Identical outfits photograph like a uniform.
Fabric: anything that moves
There is almost always wind in the hills, and fabric that catches it does half my job for me. A skirt or a long dress with some weight and flow will give you movement in every frame. Stiff, structured clothing stays exactly where it is and looks like it.
Shoes: bring two pairs
Wear something you can actually walk in and carry the nice ones. Every good spot involves uneven ground, and a sunrise climb in new shoes will be the only thing either of you remembers about the morning.
The thing everybody forgets
A jacket. Nuwara Eliya is genuinely cold, especially before the mist burns off, and almost every visitor is caught out by it. You will not wear it in the photographs, but you will want it between them.
And one thing not to worry about
Being bad in front of a camera. Nearly everyone is, and I do not expect otherwise. There are no poses to hold. About twenty minutes in, people forget I am there — that is when the photographs start, and what you are wearing stops mattering at all.
If you are planning something, message me and I will give you the version of this advice that applies to your dates and your trip.