So on my first back I bought a pair of boots, vampiric scepter, and a zeal. My support freaks out on me and asks what the hell I'm building. Is this really that strange of a beginning purchase? Also, half of my team started doing the OMGs when I built one piece of armor. Thoughts?
You bring BF sword. You rush IE. That is true for literally all ADCs that don't start triforce. It's okay to build a defensive item, but try not to do it before your 3rd item.
Teams always find it weird and freak if an ADC buys armor or mr... it's like "noooooooooooooo you neeed only damage!!!!" Some people don't understand that defense is actually a good thing.
As for the start, eh... that's an alright start depending on what you can afford. Most people go straight for a BF Sword when they have enough though.
If you have enough money to buy a BF sword, buy a BF sword. Boots and a vamp scepter are great, but that zeal isn't going to be very helpful until you have more damage. Particularly for the laning phase there's a great emphasis on poking, and it's going to be easier for you to poke with an extra 50 damage for single auto attacks or as a bonus on your double shot.
To expand on some of the other answers a bit...
The BF Sword to start the IE rush is considered the standard build by most ADC mains. With a few exceptions, where you might go for BotRK first. If you watch any ADC streamers you'll see them basically follow this build start every time.
The reason for this is because if you don't come back with a BF sword on your first back, it's unlikely that your opponent will not have a BF Sword. They will then out-trade you in lane and make it difficult for you to keep up.
Miss Fortune has an advantage here as well... her movement speed buff, and attack speed buff, stops you from needing to worry about her boots for a bit longer than most others. So you can damage a bit faster than your opponent.
Also Lifesteal seems to benefit an ADC quite a bit more than armor during mid-game.Just my two cents. Still doesn't give someone the right to freak out.
Just make infinity edge, phantom dancer, blood thirster, and last whisper, in that order. Works well on virtually every adc in the game. Get your boots somewhere in there but definitely try to get a BF Sword on your first back if you can afford it. There are other builds that can be better in some situations but I think this is a great place to start.
