Just won my first game as Spectre
She is fun, but god damn am I useless in the early game. Even after it, unless I am six slotted she feels so weak.
Whats the build order on her?
Phase -> Radiance -> Manta+BKB -> Heart -> Skadi ?
Spectre does not win her lane necessarily, she survives and farms in it. If you can keep finding pockets of space to farm you are fine.
I like to go PMS, Quelling Blade, Brown Boots and a casual Ring of Health. The casual RoH is for staying in the lane longer after you run out of regen. I usually sell this later on to get a piece of my Heart or something.
A lot of people do Phase lately but I don't really like it too much just because you are already phased with dagger, and with the Treads attack speed you can get more Desolate procs. Tread switching is also useful, especially with her small mana pool. Just don't forget to be on Agility when you use Haunt unless you really need to conserve the mana.
I find BKB to usually be unnecessary on her, as I would rather just have more HP, Manta or something.
After Radiance, depending on the game you can go S&Y if you need the immediate HP and stats, or casual Yasha into Heart, then Manta after Heart. Sometimes you might have to go Manta before Heart if the are a lot of silences flying around.
After all that Skadi is great: More HP, more stats, more chasing potential, all great things on Spectre.
whatever best fits the game
and not ring of health first
Not RoH right out the gate but you should get it to survive the lane after you run out of regen.