BEHOLD THE MIGHTY THREAD NECROMANCER!
I, both as a DM and as a player, enjoy very much improvised actions, and I've come up with a solution for adjudicating "tricky" actions, using base attacks as a standard. An improvisation has a usefulness factor: sometimes, the effects are greater than an attack's; sometimes, the effects are lesser and predictable.
1- increased effects are major advantages in battle, so they have disadvantage on the skill check needed to succeed, or come with a cost. For example, immobilizing a foe's arm (thus impeding it to attack with said hand) requires a Grapple with disadvantage. Or two successive grapples.
2- Small effects have little impact on the game, but they are like small stings in a fight. They are handled with advantage, or as a bonus action. One example is a "careful attack": you attack with advantage, but you don't add your Stat modifier to the damage done. Useful for taking down heavily armored enemies, not so much for low armor but high hit points.
3- Tradeoffs when an action has a fair tradeoff with an attack (such as blinding an enemy with a puff of pepper) you expend an appropriate action, replacing your base attack and use a skill or grant a Saving Throw.
4- Kairós, or opportunity in ancient greek: the same as above, but with a greater effect/without disadvantage/better action economy. It is a one-shot, triggered by specific circumstances.
I, as a DM, also allow to make "strong attacks" and "Careful attacks" as variations. A Strong attack doubles the damage dice, but hits at disadvantage. "Careful attacks", as I said above, have advantage to hit, but don't add any modifiers to the damage roll. Until now, it works beautifully.
A list of my impros as a strong fighter:
a) Grapple, and then bash the head of the opponent against a wall/floor to stun.
b) Shove and then grapple the mouth of a caster to silence it (with disadvantage: I killed a high priest this way)
c) Throwing very big rocks against my enemies from higher ground.
d) Using caltrops or fire, and then shove my enemies against it.
e) Setting spider webs on fire.
f) Shoving an enemy against another to trip them both.
g) Goring enemies, and then intimidate the ones alive screaming at them.
h) Very close quarters, using a dagger as my weapon, to grant disadvantage to my enemies.
i) Sand to the eyes.
j) Kicking the kneecaps (a disarmed attack that grants a Con save or halves the speed of my enemy).
k) Forming a shield wall with my companions/hirelings.
l) attacking the hands of the enemies to impede them casting/using weapons.
m) Using smoke to provoke coughing and impede vision.
...etc.
And then the rest of the tricks of a savy fighter, like disarming; being prone and seek cover to evade projectiles; attacking with a lance from horseback (120 feet every round, more than enough to attack with reach and then retire to safety without disengage), attacking with a bow from horseback; trampling enemies with my warhorse, fight in the bushes; grapple people and drowing them with only my movement; grappling and then throw people from very high grounds; grapple then stomping people against stakes, spikes or anything pointy; set things on fire with oil and torches; etc.
There is so much you can do within the rules that only saying "I attack" is boring. Of course, a fair share of my combat time is expended by making attacks (although I've given a lot of mileage to my Shield Master feat... so much GREATNESS can be done by having advantage on most of your attacks, specially if your companion is a dual-wielder champion and he crits half of the time), but at least half of it I seek any advantage I could take.
