I know some people like to go Warrior on trinity force. I am not the biggest fan on warrior but if i get some kills i go for trinity force as my second item.
For boots i go swiftness all the way unless they have a lot of ap so i go Ionia and visage for the 40% cdr.
One item i build when i start playing Skarner whas the black cleaver. So if you wanna fell unique.

I see people go ghost. i don't have a lot of experience whit it.
And if you wanna go top lane Tp and sunfire cape as a first item