Rush Catalyst, then build Banshees, not Rod of Ages. Most Singed's build RoA, but FD insists that BV is superior on Singed, and his and Realo's Singed records definitely make me think there's something there.
Beyond that, I'm not sure. I think Boots of Swiftness is what you should go for, but I might be wrong. Singed is a lot about mobility and positioning, and taking advantage of poor positioning of the enemy team. Don't go "OH ENEMY LET ME FLING YESSSSSSSSSS" - instead be patient and set yourself up well so that you fling one of their squishies out of the fight (preferably into your team). You should feel comfortable tower diving, and you should be running past minion waves so they all get poisoned.
Beyond that, I don't have much for ya because I haven't played the guy very much.
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~AHylian is Still Alive~