Unfortunately, it is almost impossible for every one of your team mates to win their lane.
As a support, I have tried to support everybody equally. Sadly, that tactic did not go over very well, and cost me a few team fights and possibly games.

So, the game of favorites is to pick 2-3 allies you will keep an eye on the entire game and support specifically them to ensure they get fed.

If your ADC is terrible at csing and doesn't understand how to play safe but your mid laner is already 3/0 at 8 minutes, leave your lane. Whenever you see a chance, go roam mid and hope to get your mid laner a kill. If your ADC dies in their lane but they were pushed up with the wave, that's their fault.

Burst Damage

When Lulu is supporting an ADC that revolves around burst damage, like Caitlyn, she doesn't necessarily need attack speed.

During the laning phase, your W should be saved for polymorph, not attack speed.
Lulu's W cooldown is pretty long, so taking full advantage of that polymorph is important.
With this in mind, during a fight you should polymorph the ADC (or support if they are more of a threat) as soon as your ADC begins autoing them.
This allows your ADC to get a few extra hits on your opponent.

Lulu's Q does a good amount of damage in the early game, so use that to your advantage. Poke the enemies down with your Q, but don't waste all your mana.

Attack Speed

Instead of using your W to instantly polymorph the enemy, save it to boost your ADC's attack speed. Your ally has more of an advantage and can land more autos than the enemy, exactly like the guide for burst damage, except you W your ADC.

Lulu's Q does a good amount of damage in the early game, so use that to your advantage. Poke the enemies down with your Q, but don't waste all your mana.

Lulu's mana absolutely sucks during laning phase.
In order to conserve your mana and be able to stay in lane longer, you'll have to pick and choose which abilities you want to shield you and your ADC from.

If it's an auto that does very little damage, don't waste your mana. But if it's a fully charged Varus Q, you'll want to pop that shield.

This is an obvious one, but always keep in mind how much mana you have before you fight in botlane. I've made many mistakes with this one, unfortunately, and it costed us a lot.