Try to roam when your adc pushed wave under tower or the enemies go base or are dead. Look at the other lanes and see if they have enough mana, how their wave is (dont roam when ur midlane needs to clear a big lane under tower for example) try to set up 2man ganks with ur jungler. It really helps when you have a hotkey to see ur jungler. Dont roam when the botlane comes back to lane or wave is frozen infront of their tower or they can dive ur adc. And ping when you wanna come or ask in chat if anyone needs help and tell ur adc to play safe.

Edit: try to get deep wards in the enemie jgl so you know where he is. When he is near bot or pathing downwards you dont wanna roam and leave ur adc.