You will problaly go for mecurys threads if they have many CC. If not go for the berserks greaves. You can go for a trinity force as well. You can build an frozen mallet instead of a infinty edge. if you need a tank build tamky and if you need damage then build damage. Lee sin needs to be with teammates often cause he isnt THAT strong himself if you 1v1 him.

You will gang at lvl 3. You might start with golems. Then Wraiths, Then red buff, Wolves and finally give your blue to your ap carry or (mid). When you attack you go with your "E" wait 2 seconds and press "E" again. Do that will all of your abilitys be4 just spamming them all up. Your passive and the lantern will keep you at almost full health all the time;D