Get 1 level of Arcane Hide first if you are babysitting (harassing for, healing and denying for a lategamer so that their early game isn't so difficult, letting them get the last hits and kills in the lane) and use it if the enemy is ganking or casting a spell on your buddy. If you end up solo it's not as important.
Ring of The Teacher +x1 set of runes
After that farm towards a ring of sorcery (disassemble the ring of the teacher for the guardian ring, keep the scarab for bonus mana regen), the mana lets you spam your quick refresh spells to better support your team late early and early mid. Get marchers and a few bracelets then go for a Totem of Kundra and Post Haste. The disable and extra mobility are very powerful, especially considering your heal deals diffusing damage around all units that it heals, letting you wipe out creepwaves in one cast.
Using your abilities:
Entangle: Use it to harass enemies or slow for a gank. If someone is trying to escape a teamfight use it on them, in the start of a teamfight try to use it on someone who is channeling or is trying to cast a spell, as it has a ministun that interrupts both actions and may disorient them. Also, if you're running from a gank it might be worth turning around and using it on them to slow their chase.
Heal: Use it to heal (obviously lol) and to deal damage around your heal target. Heals more and deals more damage the more units are around you so it's best in lane fights with lots of creeps.
Arcane Hide: Put it on people initiating ganks and teamfights or people running from ganks or teamfights. Also if you see a spell flying towards someone if you're quick you can put it on your teammate and absorb some of the damage. Very good if you get it on someone right before a pyromancer combo or something of the sort.
Storm Cloud: Pretty obvious here, drop it in the middle of a team fight right after it has been initiated. Helps friendlies and hurts enemies. You can also use it on ganks, the refresh isn't too long and it can be pretty helpful alongside your heal and arcane hide for keeping your friendly runners alive.