With a swashbuckler your primary stats are dex & cha but inspired blade complicates that a bit since intelligence now combines with charisma to determine your penashe points.
Also, unless your GM allows in Fencing grace, there's no good way to get dex to damage with your rapier until you can add agile to your weapon.
If your GM goes with fencing grace take that feat at 1st level and you'll be using dex to both hit and damage so you can max out dex and leave str alone.
At 5th level you get the improved critical feat for free (normally an 8th level feat) so you'll be criting on 15-20.
If you go the high dex route be sure to watch what armor you wear to make sure it has a high enough dex allowance. One of my characters is currently drooling over some leaf armor.
Also be aware swashbucklers have terrible saves (except for reflex) so picking a trait that buffs your will save a bit (there are a number to chose from) might be a good idea. You get bonus feats every 4 levels so a human starting at 5th level will have 4 feats to play with. Its worth considering using 1 of them toward improving your will save.
As for the 4 feats
Fencing grace is a must (you get weapon finesse for free)
Combat reflexes is another (gives you multiple attacks of opportunity)
Step up is one I like (if an opponent takes a 5' step away from you, you get to follow)
Weapon focus is a prerequisite for many other combat feats (gives +1 to attack rolls)
There are way to many more to list.
Anyway, that's the advise from someone who has made exactly 1 inspired blade swashbuckler.
Morag
Since the Inspired Blade's panache pool gains (minimum 1) from both intelligence and charisma, you can choose to focus on one and ignore the other if you want. Any intelligence or charisma score below 14 adds 1 to your panache pool, period. So an Inspired Blade can dump one of the two without worry - the Bruising Intellect trait allows intimidating with intelligence too if one is so inclined.
It's of course quite possible to do a Crane Style Swashbuckler for some absurd parrying action.
I've played 5 sessions with the same (Inspired Blade 20 point buy starting at level 5.) You can do a lot of damage if you build right - my GM has had to audit my character because the party couldn't believe I was doing so much damage.
strength 14, dexterity 16+1, constitution 12, intelligence 10, wisdom 8, charisma 16
1: Power Attack, Combat Reflexes, Weapon Focus (rapier)
3: Steadfast Personality
4: Weapon Specialization (rapier)
5: Step Up
7: Weapon Versatility?
8: Greater Weapon Focus?
9: Critical Focus
gear:
+1 rapier, +1 mithral shirt, +1 buckler, Quick Runner's Shirt, Swordmaster's Flair (blue scarf)
There's a lot of back-and-forth about Power Attack - long story short, it's not usually worth it when you're full-attacking without buffs or bonuses, but if you're making a single attack, or flanking, or attacking someone prone, or fighting someone with DR, it is very valuable.