General DiscussionSpectre

For me, I would go phase,aquila/vanguard(skip it if your confident you won't be bursted down) ,rad/difu(preferably rad for faster farm), manta, heart,abysal
Earlygame, you should always be aware of the map, look for ez kill secures using your ult. Anyways hero is pretty straight forward, just farm, and when your team starts clashing, pop your ult, rinse and repeat

You afk farm and join teamfight with haunt when the time is right
For pub urn is good
Phase boots for mobility
Threads for farming
Pick one that fits your playstyle
Skill is 12311 ult 1 then max 2 then 3 usually
After urn go for radi if you wanna afk farm
If the game goes uber dogshit that you cant get a 25 min or less radi just go for cost efficient items like diffusal,then manta
Manta is a must have
You carry by procing desolate on solo enemies (add more AS)
Or spread AoE damage during teamfight (add more health)

Consider refresher on stash if you're just too damn fat and wants some extra swag

900 spectre game here

well to be honest, russianpinoy already told you all of it

what you need is a good dedicated support and good teammates that can create a good teamfight/gank so you can haunt in and get the gold.

Recently i always go phase-urn-drum-pms-quelblade-diffusal then manta

but now i think it was not really suited my playstyle and i now try to go to radience old build again

kinda risky i think, going phase-urn-magicstick-quelblade-pms and save my money for radience-manta-abysal or diffusal if the enemy make ghost staff(tarasque is also good for tanking but i feel abysal/diffusal was more important), if i took to much pressure well no choice going to diffusal-manta route

usually if the game go ultra late game you can abuse the spectre stash inventory fountain trick, kinda simple i think.

just buy bkb, then you active it, swap the bkb with your more useful core item(if you had full slot), and haunt in.

but that scenario was very rare i guess

This is all good advice. If you need more in-depth advice, read my guide: http://www.dotafire.com/dota-2/guide/how-to-win-with-spectre-on-your-team-22728

Skip ulti at 11. Extra second of illusions not worth it over upping a skill

if you want to try something different get a maelstrom with an early orb of venom+urn and go 1-3-1 skill build. depending on how the game goes, pick up a vanguard in between maelstrom upgrade. then you can just creep skip with the mjonllnir active and your dispersion.

Treads -> armlet -> radiance -> heart -> manta and other items

Ive never tried this but it seema a fun build