If your playgroup likes extra little tactical nuggets, your GM can allow you to try out some of these additional variants to add some more spice to your game. You can always try out a rule for 1 session and see how you all like it before committing to it.
Multiclassing
If your GM wants to allow for additional creativity for experienced players (and potentially broken combos!), when heroes level up, they may choose any class. For example, when a level 4 Berserker levels up, he could pick Commander, and take the level 1 Commander features instead of the level 5 Berserker features. He would have 4 d12 hit dice and a single d10 hit die. A hero gains all the equipment proficiencies of all their classes but should use the advantaged/disadvantaged saves of whichever class has the highest level.
"Broken" Can Be Fun! Planning, building, optimizing, and “breaking” a class build IS the fun for many people. The GM may need to make the game substantially more challenging if multiclassing is allowed. The GM also may veto any particularly overpowered, unfun, or implausible combo for the sake of the story and overall fun of the table. If this happens, well done! Your hero was too powerful for reality.
Small Groups
A GM and a single hero can play with the aid of a sidekick. Sidekicks are NPCs that the hero’s player controls during combat and the GM controls outside of combat. Sidekicks get 2 actions and are always 1 level below the hero character. If the main hero dies, the sidekick can be upgraded 1 level, and hire his own sidekick to keep the adventure going! A GM can optionally allow one or two sidekicks with a party of 2-3 heroes as well.
Large Groups
3rd party adventures are typically balanced for parties of 3-5 players. Playing with very large groups (6–10+ heroes) can be made far more manageable simply by limiting each hero’s actions to 2 instead of 3. No other rebalancing needs to be done.
Fast Resting
For a much more heroic and fast-paced story, a Safe Rest can heal all Wounds.
Critical Healing
Treat healing just like an attack roll. Rolling the max is a crit (rolling again just like an attack crit), rolling 1 is a failure to heal (note: this variant is FUN for the right group that enjoys big, dramatic, swingy moments). Consider increment the die size by one step if you use this variant (d4 » d6 » d8 » d10 » d12).
I Had the High Ground
Taking a crit while at a height may cause a character to fall down. A reasonable STR save may be called for, but a weak character (e.g., a kobold) may just fall automatically.
Thrown Potions
Treat potions like Ranged attacks (Range 8). The potion misses on a 1; otherwise it heals for half as much since some splashes away and is wasted.
Sucker Punch
A character standing up from Prone gives adjacent enemies the chance to take opportunity attacks (heroes and monsters alike).
Playing Dead
Whenever a Hero drops to 0 HP, they can attempt to play dead by falling prone and making an Influence check (or other skill check as the situation demands).
Inspiration
Whenever a hero does something memorable (role-plays a great moment, makes everyone laugh, miss an attack multiple times in a row, or otherwise engages in desired behavior), the GM can grant Inspiration: the ability to reroll any single die. Inspiration expires after a Safe Rest.
Retreat
The world is dangerous, and some fights may be unwinnable. Any hero may call for a retreat on their turn. If the party agrees—unless there is a good reason story-wise that a party can’t escape (e.g., they are trapped in nets and completely surrounded by a band of nasty kobolds)—the GM allows them to flee. Each hero describes their escape (e.g., casting a spell, using equipment, or making a skill check). Consequences may follow, such as taking damage, suffering a Wound, or failing a quest. If the escape is particularly clever, the GM may allow the party to escape without additional consequence. After all, the shame of retreating is often punishment enough!
Different Key Stats
Players can swap KEY or Secondary stats for a class if it makes sense (e.g., DEX and WIL for the Cheat).
Complex Characters
A GM may allow heroes to pick 2 backgrounds and/or ancestry bonuses.
Custom Weapon Dice
For larger weapon die sizes, you can try using dice of a different size as long as they add up to the same initial die size. For example: a 1d10 glaive could be 1d4+1d6 or 1d6+1d4 (using the first die as the primary die).