The question is: Why not? Is it viable in ranked? NO. Is it good? Not as good as anything else. But why not try it? Hell, I might even try it.

I'll give it to you short and sweet.

Laning: Just play him a couple of games, you'll figure it out, trust me. One tip is:
Don't be afraid to throw out Q's, not like you'll run out of mana amiright.

When to Roam: Either when the enemy Botlane isn't there, or when you have no mana
and are sure that your ADC isn't going to die while you leave.
DO NOT just roam for the chimes. I repeat DO NOT *JUST* roam for them.
If you want to get them, why not visit Midlane while you are at it? Or
why not help your jungler with scuttle? Just make sure you aren't gone
for too long

How to use your W: Just place it all over the lane lol. If you roam mid, just place one there as well. And remember, if you already placed 3 ( Which is your max), you can place your W on yourself or a teammate and it won't remove an existing one.

How to use your E: First of all, you can E out of Spawn. Just try it in the Practice tool. You will forget to do that a lot. I do too. If you forget, you have a second chance a bit further in the lane. You'll know what I mean.
A little Trick: If an enemy goes through your E, you can Q him for free, even when you think you threw the Q out too early, it still will hit ( probably )
And if you are really advanced you can stand next to your E and maybe the enemies will misclick and go through it. Who knows.

How to use your R: Your Ult is a dangerous ability. You can throw or win team fights all by yourself. You'll either get pinged for how great your ult is, or for how much you just threw the game. And remember, it's all your fault :). All I can tell you is, don't ult if you think one of your assassins is gonna burst their ADC down.
But when should you use your Ult? You can ult someone while the enemy is disengaging and kill them while they are caught out. Also, you can Ult their Front/Backline to kill the rest while they can't do anything. Be creative. Be BARD

There isn't a lot to say. All of it is sub-optimal, but you might have some great fun with the damage output.

Most of it is self-explanatory as well, Morello's for anti-heal, Zhonya's to not get bursted down easily, and Everfrost if you hate fun, which is fun.

I can't say I'm a high elo Bard main. So why trust me? Just trust me, trust me.
(Source: Just trust me Bro)