I really loved my perks in Fallout 3 and it really added an exciting new dimension to levelling. Wondering why it hasnt been implemented earlier in the Elderscrolls!
I was wondering how they could be improved in Skyrim. What about linking some of them to factions? Some of those perks require a minimum score in a stat. What about making them so that they require a certain rank in a certain faction. For instance an advanced bonus to a murderous technique could only be learnt if a high ranking member of the dark brotherhood... It could be even taken further. Some might require to be bought at faction vendor.

IMO since perks are limited, they should not be required for factions. In fact, no skill level should, just your ability to do something for them (like wipe out a certain dungeon), which might be extremely hard at a lower skill level. Doesn't really make sense for them to say "No, you can't rise in rank, I mean you may have done everything perfectly, but your skill level is apparently too low". Also, perks should be not linked the other way either. Anyone should be able to learn a perk if they are skilled in it. Though I wouldn't mind "special techniques" as a seperate aspect that factions must teach you.

I don't mean perks linked to faction ranks as required to advance in ranks but that choosing a perk requires having a certain rank. The way I see it, factions somehow replace classes. . Insofar as for instance, if you want to be a thief you have to join the thieve guild. There you will be able to live the life of a thieves being sent on assignement that requires your thieves skills. At the same time you can live it as a freelancer you can just pick people's pockets break into people's houses. But of course you don't get immersed that much into the thief thing. Its more like a kleptomaniac, on the side bonus than a real career in this case. I hope guilds encourage people to specialize in certain skills ( unlike Oblivion )
Of course it all depends on the number of skill perks available. If you have limited perks for picking locks that are very useful. You may not want to require players to go through the whole thieves guild run to be able to acquire them. But a few distinct special bonuses that rewards players for their time dedicated to their faction(s).

At the same time, each leveling could grant a perk point which would have to be spent at a trainer to acquire a perk.Same as you acquire spells. Daggerfall used to have a lot of faction trainers. Some freelance trainers could be added ( more expensive) for those not willing to join all factions..

At the same time I disagree with your point of view. I don't see the point of the Mage guild giving ranks to a guy emptying a dungeon with his sword for them. You could earn a special status.. sergeant of the mage guild guards for instance as Mages need some swords to lend them a hand from times to times but I dont see a Mage guild , dedicated to the learning of the Magic arts, giving responsibilities to someone who doesn't understand magic... Same as you wouldn't let the janitor teach literature or become the principal in a school even if he does his job perfectly ( Maybe Willie the Scotsman will replace Skinner as principal one of these days )