Do...

Get boots +3 pots to start.

Rush a Vamp Scepter before your level 2 boots. You need this for sustainability.

Rush IE. This maxes your damage quickly.

Rush PD, after IE. Getting more crits, and AS boosts your DPS faster than building bloodthirster.

Don't...

Get Doran's Blade. It is bad compared to all of the other ADC items out there.

Rish RH, over IE/PD. (Unless you are Varus/Teemo) RH. Dealing damage to three enemies at once sounds great, until you realize that you've just made the damage you deal to single targets much much lower.

Build Tri-Force. (Unless you are Corki/Ez.)

Correction: Add rush BT to the 'don't' list. Add Rush PD to the 'do' list.

Idk, I think Doran's Ring gives ADC's that all important AP and mana regen required to stay viable early game.
Seriously, though, read what you write, it's Doran's Blade, not Doran's Ring.

Looks like my support has some bad advice.

You want damage and survivability before you want movespeed/crit/aspd.

Sorry, but you're wrong. Never rush PD, ever.

That said, Infinity Edge is slightly superior to Blood Thirster unless you

a. Can farm like a boss right after you buy it.
b. Can stay alive to keep stacks on it.

After it gets fully stacked it provides more than Infinity Edge, but Infinity Edge is stronger right when you buy it. IE also synergizes better with PD.

Also, Trinity force is NOT a bad item on a select few ADC's... Namely Ezreal, Corki, and sometimes Sivir.

Maybe I should change it to... Don't rush triforce over IE, Vamp Scepter, Boots, etc. I just hate it when people rush tri-force, and have zero damage or sustian.

A friendly message to support's who don't know what AD carries should build in certain situations:

Don't tell us what to do.

Actually, I've seen Ezreals be very successful rushing Trinity Force if they are doing well. All you need for Sustain is a Vamp Scepter.

don't rush PD? once you get IE your crit is suddenly 250% damage, which means any crit chance increase is now worth much more than before. This is why you go IE>PD>BT, some ADC have skills that scale well with attack speed, for those they could go PD>IE>BT.

Name a single ADC who benefits more from PD > IE/BT.

Kog'maw is the only one I could possibly see an argument for.

If you say Vayne, you're wrong.