Play as Serana; Dawnguard Preset 1.0

Play as the feisty and sarcastic vampire princess of the Volkihar Clan. Or perhaps her twin sister or doppleganger.

The last preset of the Nord Female should set you as Serana.

Roleplaying: If you really want to do it right, install 'Serana-ish Vampires Paler Vampires' listed below, join the Dawnguard and play up until becoming a Vampire Lord(/Lady) , and then go out and have fun.

Gear: type 'coc qasmoke' in the console (and coc riverwood to leave), and grab a few things. The dark sleeved Vampire Royal Armor, Vampire Boots, an Elven Dagger, and the spell tome for Ice Shard. That way you will be equipped as Serana should be.

-Required-

Dawnguard.

-Optional-

http://skyrim.nexusmods.com/mods/29063/

This mod gives a few of the other Volkihar, including the player, the same detailed eyes as Serana and 'fixes' the dark skinned bug I believe. Relevant to this mod, it doesn't take away the PC Serana's eyes and replace them with the boring default ones. Side effects: It makes a few of the elven vampires look a bit googly eyed, but In my view its an acceptabel sacrifice.