Measure before you buy. A garland draped on a mantel needs extra length for the swag and for the ends to hang down the sides; a 6 ft mantel often needs about 9 ft of garland. Staircases need the length of the handrail plus extra for each swag. Common garland lengths are 6 and 9 ft, and you can join several.
Fullness is listed by tip count or diameter. A thicker garland looks richer on a mantel, while a slimmer one is easier to wrap around railings and door frames.
Pre-lit garlands usually use battery packs with timers, which avoids cords trailing down the mantel. Plain garlands let you add your own fairy lights, ribbon and ornaments. Fluff each branch before hanging so the garland looks fuller and even. Compare fullness only between garlands of the same length.
Secure garlands with adhesive hooks, mantel clips or zip ties rather than nails. Match the greenery to your wreath so the decor looks consistent.