First of all, I'm not good at English.
[slayer-jinx-wink]
Second, you can buy some control wards.
Third, you should play all the lanes to understand macro.
(Since supp is a sort of jg/mid.)
If you have finished pushing your minions, you can roam.
Put your wards.
If your mid lane is" freezed", there should be many minions in front of your tower.
You can deal some damages to the minions. (Don't take the last hit, though.)
(It's basically a jg's job.)
If you get the 1st tower, get the drake or herald. Go for the other lanes.
If you are behind, protect the herald from being captured by the enemy team.
(But you cannot leave your adc alone, if you are still getting your 1st bot tower.)
If you get bot and mid towers, invade the enemy jungle for snowballing with your teammates.
And ward there. Your team gets extra exps/golds, enemy team lose them.
After that, you recall, on your way back to the lane, mid gets your blue buff,
adc gets your red, and so on.
While your teammates are farming in the jungle, sup places wards.
When you are way behind, you have to take back the control of your jungle.
To do that, you can place wards at first. Recall back again to refill your wards.
Do it quick before the enemies come back. But be cautious.
The first wards would be destroyed by the enemy, but you can replace with your new ones.
Tower Siege?
You should be able to "dive" to the tower sometimes.
You take the damage from the tower, your team goes in, kill the enemies.
When the enemy has "wave clear", invade the jungle.
Want to get Baron?
Push the mid lane first.
And you have to take the control of the enemy jungle.
Where are the enemies? Are they dead?
How many enemies are in the bot lane?
Where is the enemy jg?
Your Baron is in danger of stealing?
You have to protect your jg.
You have to kill the enemy jg.
Because Smite matters.
lol is basically an object-trading game.
You don't need to protect all the towers. Don't do that.
Just keep trading towers when you are winning.
There are much more you can take care of.
Good luck.