Lighting After Dark

A field at eleven at night is genuinely, completely dark. Most couples underestimate this by a wide margin.
Three Jobs, Not One
Lighting has to do three separate things and people usually only budget for the pretty one. There is atmosphere inside the marquee, there is task lighting for the bar and the food and the loos, and there is safety lighting on every path between them.
The third is the one that gets missed, and it is the one that causes falls. Anywhere a guest walks between two buildings after dark needs light at ankle height.
Festoons Do the Heavy Lifting
Warm festoon strung above head height is the most reliable atmosphere lighting there is, indoors or out, and it photographs beautifully. Uplighters on the marquee walls add depth and cost little.
Avoid anything colour-changing. It looks like a function room within twenty minutes and it ruins every photograph taken after sunset.
Power, and the Generator Nobody Costed
A field has no power. Lighting, a band, a caterer's kitchen and a bar between them need more generator than couples expect, and a generator that is running at its limit is a generator that cuts out during the first dance.
Get the supplier list to your marquee company early and let them size it. Then ask where the generator sits, because they are loud and the default position is usually behind the marquee, which is where the speeches are.