String lights do something no other outdoor fixture manages: they turn an ordinary patio into somewhere people want to stay after dark. Hung well, they light a whole outdoor room from above with no glare at all.
Hanging them properly
Height — 8 to 10 feet above the ground. Low enough to feel enclosed, high enough to walk under.
Support — use a stainless steel guide wire and let the string hang from it. A string taking its own weight will sag and eventually snap at the socket.
Drape — let each run dip about 18 to 24 inches in the middle. A straight, taut line looks stiff.
Pattern — zigzag across a square patio, or run parallel lines down a long deck.
Commercial grade is worth it
The difference is the cord. Commercial-grade string lights use thicker gauge wire and moulded sockets that keep water out. They also let you connect several runs end to end, which the cheap versions cannot handle without overloading. A run that survives three winters costs less than three runs that each survive one.
Patio size
Total length
10 x 10 ft
~48 ft
12 x 16 ft
~96 ft
16 x 20 ft
~150 ft
Bulbs
Shatterproof LED bulbs are the right call outdoors — they survive being knocked, they run cool, and at 2700K they give the warm glow the whole effect depends on. Look for dimmable if you want the same patio to work for dinner and for a party.