If you are filling large spaces, even arrangements with nothing but greenery are beautiful and very cost effective.
Greens can be done several days in advance. Simply spray with a leaf polish when finished. Do not spray Leafshine on flowers, however, there is a gentler sealant made especially for flowers.
Greens may need to be washed when arriving dry packed from the field. Hard water tends to leave a splotchy white residue on leaves.
Leafshine removes that and leaves a cleaned, glossy finish that lasts a long time in regular temperatures. I do have smaller cans that are available so is cheaper for a single wedding.