A few things I’ve learnt from playing as a Support:
1. Don’t feed by showing in lane and greedily farming multiple waves of creeps
(unless you’re creating space worth your death). If it feels like you’re “pushing the lane” you actually could just be a just a greedy pig.
2.If you find an enemy sentry on a high-ground ward spot, don’t kill it: place an observer ward there and beg your team to leave the enemy sentry alone.
3. Full mana during laning stage = major pussy alert.
4. Buy sentries as starting items especially if invis heroes on map.
5. Use observer vision in mid lane to scout out mid lane obs wards.
6. After dying, TP back to lane for XP, but also bear in mind that TP may be needed to save your mid / other lane from GANK.
7. My own: as a support in the offlane, if the enemy messes up their lane and a big push comes down early, it can be a good time to leave the lane and GANK mid. This helps win mid and also gives your offlane core some high XP while the enemy is trying to pull their lane and recover balance.