If you're going to put a lot of ranks in Persuade or Intimidate....
You'd better damn well be able to play a Persuasive or Intimidating PC.
I'll usually ignore persuade checks if they're used in the context of
'Follow me. [Persuade: 52]'
Just sticking ranks into persuade isn't enough in my book.
Speaking of books, how about The Rulebook?
Persuade replaces Diplomacy. Here's the SRD text on 'Diplomacy'.
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Diplomacy
You can change the attitudes of others (nonplayer characters) with a successful Diplomacy check; see the Influencing NPC Attitudes sidebar, below, for basic DCs. In negotiations, participants roll opposed Diplomacy checks, and the winner gains the advantage. Opposed checks also resolve situations when two advocates or diplomats plead opposite cases in a hearing before a third party.
Action
Changing others’ attitudes with Diplomacy generally takes at least 1 full minute (10 consecutive full-round actions). In some situations, this time requirement may greatly increase. A rushed Diplomacy check can be made as a full-round action, but you take a -10 penalty on the check.
New Attitude (DC to achieve)
Initial Attitude
Hostile Unfriendly Indifferent Friendly Helpful
Hostile Less than 20 20 25 35 50
Unfriendly Less than 5 5 15 25 40
Indifferent — Less than 1 1 15 30
Friendly — — Less than 1 1 20
Helpful — — — Less than 1 1
Attitude Means Possible Actions
Hostile Will take risks to hurt you Attack, interfere, berate, flee
Unfriendly Wishes you ill Mislead, gossip, avoid, watch suspiciously, insult
Indifferent Doesn’t much care Socially expected interaction
Friendly Wishes you well Chat, advise, offer limited help, advocate
Helpful Will take risks to help you Protect, back up, heal, aid
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This means that, going by the book, Persuade makes people like you a bit more. It does not convince them of anything. It makes them more likely to believe you, help you, or follow instructions, but you need to get around a 40 to make someone go from Unfriendly to Helpful. In fact, in this module I'd use even higher scores, since we've butchered both Bluff and Diplomacy together into 'All Purpose Social Skill'.