Starts with Scott Brooks. Drop Brooks, add a competent HC (Stan Van Gundy, etc.), and they'll instantly be a better team.
Trade Kevin Durant. That guy is a choker and loser. Not clutch whatsoever. They need to cut him loose before everyone else realizes it (if they have not already.) One guy they could use is Kevin Martin. Straight up. Durant for Martin.
Call me crazy but I think the current OKC is done. They already have Perkins locked up to 10M a year, WB and KD are making the max. Can they afford Harden and Ibaka as well?