I like the relaxing playstyle that Yuumi offers. In lane you can do a surprising amount of zoning, and damage to mele support lanes if they can't threaten you with cc giving you a chance to get your spellthief's gold. The basic laning on Yuumi is wait for the enemy to waste all cc threats they can stop you from reattaching to your adc with and then auto them for your passive mana and shield and then hop back on your adc whenever the enemy lane poses a damage/cc threat. Late game it on a champ that can 1v9 with you and wait for the lp to roll in. Remember that you can get out and block non cc abilities for your adc in a close fight and get creative with ways to reduce the enemies dps with blocks. Warding alone is quite dangerous if you don't know where the jungle is so trying to ward with someone with mobility is best.

https://youtu.be/EvEFFjMTip8