Every character begins each session with Inspiration, which is a thing you either have or you don’t.
If you have Inspiration, you can spend it at any time to take an Inspired Action provided that action somehow ties into one of your character’s personal characteristics. If your Ideal is “I will do anything to save a person in danger,” and you want to swing across a ravine on a vine to rescue someone who is about fall into the ravine and hanging by one hand, that fits. You can claim an Inspired Action.
When you take an Inspired Action, you can either gain advantage on an ability check, attack roll, or saving throw OR you can give advantage to someone else’s ability check, attack roll, or saving throw provided you are in a position to assist them directly in some way OR impose disadvantage on someone else’s ability check, attack roll, or saving throw provided you are in a position to hinder their action directly in some way. Whatever it is, the Inspired Action MUST somehow connect to one of your Personal Characteristics.
So, let’s take that “I will take any risk to save a person in danger.” You could do the aforementioned “swinging across the ravine to catch them from falling” thing. Or if they have to attempt a saving throw to avoid a collapsing ceiling, you could throw yourself at them to save them, giving them advantage on the saving throw. Or if a monster is about to attack someone standing near you, you can interpose yourself and give the monster disadvantage on the attack roll. See? Easy.
When you don’t have Inspiration, you can Claim a Setback to gain Inspiration. To Claim a Setback you must either impose disadvantage on one of your own ability checks, saving throws, or attack rolls based on one of your Personal Characteristics OR make a decision that creates a significant story setback, obstacle, or hindrance. When you want to Claim a Setback, simply ask the GM. For example: “I’m easily distracted by shiny objects, so I’m distracted by the giant pile of treasure. Can I Claim a Setback and take disadvantage on my saving throw against the dragon’s fire breath?” Or: “This guy wants to help us, but I distrust all strangers. I’m going to be rude and accusatory of him. Can I Claim a Setback for that?” And then the GM might have the stranger refuse to help or get offended or start a fight. Whatever.
After you Claim a Setback, you get Inspiration. You can use the Inspiration to take an Inspired Action. And on and on it goes.
This simple system uses the same basic elements as the one in the core rules, but it avoids several of the problems and it has several advantages.
First, everyone has Inspiration at least once per session because they start each session with Inspiration to spend. Everyone gets one freebie. Just as the DMG advises.
Second, it creates a strong connection between the action or choice that the player makes and the bonus itself. Inspiration becomes a little less versatile but it becomes a powerful driver of character. In return for that, you can use it to help or hinder others instead of just using it yourself or passing it along.
Third, it takes responsibility for Inspiration AWAY from the GM. Why is this a good thing? Well, for a few reasons. Firstly, it means the GM doesn’t have to keep track of it and can’t forget about. Secondly, it means the GM can’t start using it in crazy, random, or confusing ways. The connection between character traits and inspiration is right in front of the players. They understand how playing their character provides them advantages. Which is precisely what you want to do.
Fourth, it encourages the players to create Characteristics that actually will affect the game. Bonds with your hometown are nice and all, but if the game will never take place in your hometown, it’s just a wasted sentence. But a Bond with a faction that is important in the campaign? That has a real impact. And players will want Characteristics that provide an impact: positive and negative.
Fifth, players can decide how much they want to engage with the system. Inspiration and personality mechanics are not for everyone. That’s fine. And some players are inclined to ignore it. Especially when it’s in the GM’s control. But each player begins with Inspiration they can only use by engaging with the personality system. So even though players can decide Inspiration isn’t worth bothering with, it’s hard to pass up that bonus. So, at least once per session, the player might push to use the Inspiration and get drawn into the system. They might never go so far as to Claim a Setback, but that’s fine. At least they are getting involved. And maybe, someday, they’ll want to Claim a Setback.
Sixth, the incentive is the same for the player and the character. See, I’ve seen a lot of people complain about players gaming the Inspiration system. Metagaming, if you will. And metagaming occurs when the player and the character want different things. This system aligns the goals of the player and the character. Players and characters both WANT to play to their personalities. Characters because it’s who they are and players because they can take Inspired Actions. So even if they do try to game the system, they are gaming it in a way that leads to better role-playing choices. Likewise, Claiming a Setback isn’t something that either the player or the character WANT. But characters feel a compulsion to do certain things that might be bad for them (like Flaws or tripping over Ideals) because that’s who they are. And players feel driven to suffer setbacks because they can claim advantages later. So again, gaming the system leads to a better play experience. And that, kiddos, is how you actually deal with metagaming!
So overall, with that very slight modification, you get a simple personality system that works much better than Inspiration as Written. And whether you use it or you don’t, you can still do a few other things to make Inspiration and Personal Characteristics more interesting.