Persuasion tends to be based around what an individual person would most respond to. It's conversation-dependent. Some choices will have a more favorable chance to succeed. If you have 3 Persuasion, and the difficulty for that option is 3, you succeed.
If you need 3, have only 2 Persuasion, but it's a "[Strength]" check, and your Strength meets or exceeds the target Strength, you succeed as if you had 3 Persuasion.
Some options are just plain not going to work on that target, even if you meet the attribute check.
The problem of course is that you'll need to rely on instincts to decide what choices the person you're talking to will respond to best.
