Bard is hard

Play a different support that doesn't completely rely on teammates to excel.

That's about it.

Play a champion that is not garbage

Bard is standing in a tough spot in terms of viability. Like someone mentioned it, he rellies on the complete cooperation of your team mates (communication, follow up, synchronization, etc.).

Also, from his passive to his 4 abilities, everything about Bard have downsides/weaknesses that are not so hard to counter by the enemy.

That being said, for sure he has the potential to be very beneficial to his team, I recently won 3 games with him where I had a lot of assists. It's just gonna require you much more cooperation with your team mates and practice. If there is anything specific you wanted to ask, you can do, I will answer with the (limited) knowledge I have and it will be my pleasure to help.

Pick another champ that is actually not a pain in the ass for your team to play around.

ult is more useful in a team fight if u aim it at their backline at the start of the fight so u can kill their frontline. everytime i've seen bard try to use it to save someone it failed miserably, but if u can use it to take half their team out of the fight for 2.5 seconds it's huge.