If the one of the enemy players engages try using Tempered Fate on other enemies trying to followup.
You can use Tempered Fate before the fight to catch a high priority target out of position, this is especially effective during late game rotations.
Be especially wary of ruining your teammates' ultimates when using your Tempered Fate - try to focus on delaying other enemies rushing to the fight or allies with low health.
Electrocute is the most common keystone on Bard. Electrocute is easily procced by Bard in lane because of his Meeps counting as an ability, this let's Bard do a lot of damage through short trades with only Cosmic Binding and one basic attack. Electrocute is also great for the increased burst when ganking other lanes, making the chance of killing the enemy higher than with a more poke oriented choice like Arcane Comet.
Arcane Comet can also be used for a more poke oriented playstyle in lane with its much shorter Cooldown when compared with Electrocute. Arcane Comet has great synergy with the slow from Meeps and Cosmic Binding making it very hard to dodge.
Summon Aery is a more utility oriented version of Arcane Comet with both serving as poke oriented keystones, but sacrificing some offensive power in favor of the more defensive power Summon Aery can give when used in conjunction with your Caretaker's Shrine.
While Domination is mostly taken as the primary tree for Bard because of Electrocute, there are also other runes in this tree that are great for Bard. In the first slot you almost always take Cheap Shot for the added burst since it can be reliably procced with Meeps or even Cosmic Binding. Zombie Ward is usually the choice for the second slot with its ability to give you more Vision which is always great on a support, if you want even more damage from your runes you can also run Eyeball Collection if you want. In the third slot Relentless Hunter is usually the rune of choice with Movement Speed being one of the best stats for champions who roam a lot like Bard.
Sorcery is almost always taken on Bard, either as the primary tree with Arcane Comet and Summon Aery, or as secondary when taking Electrocute. Sorcery has a variety of runes that are great for Bard. Manaflow Band allows for more poking in lane without running out of mana, making it a good choice in comination with Arcane Comet or Summon Aery. The Ultimate Hat can also be good if you want to look for more opportunities to make plays with your Tempered Fate. Celerity is also a great choice because of Bard's love for Movement Speed, making his roaming ability even better. If you want even more Movement Speed for roaming you can even grab Waterwalking, but Scorch is usually the more common choice because Bard gets plenty of Movement Speed already with his Chimes and Celerity. Scorch also gives more poke in lane and more damage when ganking other lanes making it an excellent choice.
When facing a more difficult lane matchup it might be worth taking either Resolve or Inspiration for their ability to makes surviving lane easier. Bone Plating and Second Wind is great for lanes where the enemy has a lot of damage and can make the difference between dying and surviving with a small amount of Health when the enemy goes for an all in. Biscuit Delivery is great if you're up against heavy poke especially in combination with Time Warp Tonic, but the latter can be dropped for Magical Footwear if you don't intend on roaming a lot in the early game.
Bard is commonly played as an lane bully support who utilizes massive amounts of cooldown reduction and tanky items in order to take advantage of his ability to setup teamfights from afar.
Bard can also utilize magic penetration due to the nature of his Meeps gaining large amounts of magic damage as he collects chimes. This allows items such as Abyssal Mask and Liandry's Torment to compliment the tanky nature of his build.
Boots of Mobility is a valuable item for Bard as he succeeds in his lane bullying endeavors. As this allows him to extend farther to collect more chimes and return to lane in a timely manner.