I'll just explain who each Keystone is for, in general. Rest should be pretty self-explanatory if you actually spend a few moments on it.
Warlord's Bloodlust is for Crit-based champions, plain and simple. Meaning ADCs, Yasuo, Trynda, GP...
Fervor of Battle is for people who auto-attack a lot without Crit. Should be decent on Riven, Jax, WW, if you go deep in Ferocity on them.
Deathfire Touch is for sustained damage spellcasters. For example, Corki, Karthus, Malzahar
Stormraider's Surge is for assassins and burst mages that need a way to get out or reposition after bursting. Examples include Rengar, Kha'Zix, Zed, Veigar...
Thunderlord's Decree is for burst champions that want extra damage. LeBlanc, Syndra, the ilk of those
Windspeaker's is for shield/heal-based supports. Janna, Soraka, Sona...
Grasp of the Undying is for tanky sustained fighter like the Juggernauts. Darius, Sion, defensively built Irelia, those types of champions.
Strength of the Ages is for...jungle tanks, I guess? It is rather underwhelming...
Bond of Stone is for tanky supports and champions that want to take damage for their team. Aka, Leona, Maokai, Tank Cho, Thresh, Tahm Kench
Basically, first choose your keystone, then apply masteries to pronounce strengths of your champion (for example, do I get my damage via autos or spells in tier 1 Ferocity) or shore up your weaknesses (taking the mana regen in Cunning or health regen in Resolve).