Here are some common ways guitarists try to solve
the problem of accuracy on an incredibly difficult instrument:

They concentrate on making and refining the smallest motions possible.
They tense up the rest of their body in the process of isolating the focus to the small muscles of the hand and wrist.
They hunch their shoulders and lean over the guitar.
They repress the frustration years of this creates.

They try to control all external and peripheral factors: Guitar type, strap length, standing or sitting position, type of pick, gauge of strings, action adjustment, saddle height, amp tone, volume level, band mix, ambient temperature, health and nutrition, performance conditions, vibe in venue, personal mental state.

Borrowed guitar bridge or nut sliding during string bending or vibrato wrong strap length or strap breaking during solo unwound guitar string used as backup strap gradually cutting through shirt and shoulder sleeve snagging on bridge suddenly locking up hand wrong pick dropped pick broken pick no pick pick stuck between strings finger caught between strings wrong strings dead strings sticky strings blood on strings broken strings no extra strings jar of honey spilled all over strings vintage L-5's gig bag shoulder strap breaking immediately before album release concert for 5,000 people causing guitar to fall on concrete and creating crack from tailpiece to neck which gradually splits apart during performance with action getting higher and higher amp too far away amp too close amp broken so play through bass amp or P.A. tone all wrong overdrive bypass switch broken cymbal in ear band too loud audience too loud band downstairs too loud bad monitors no monitors in-ear monitors broken so Patti is heard acoustically but Tuck is heard only through house PA 50 yards away resulting in Tuck being unavoidably out of sync with Patti by 1/6 second for whole show guitar buzz RF from nearby transmitter louder than the music itself brownouts making organ pitch fluctuate randomly over an octave range power outage equipment plugged into 230 volts immediately before show earthquake during show in high-rise outdoor desert performance at 131 degrees with sand-blasting winds sub-freezing outdoor mountaintop performance with snow storms and 40 mph winds high altitude dizziness no sleep no food too much food wrong food food poisoning fever locked bathrooms way too many liquids before long show nagging suspicion that zipper is down contact lens falling out during moment of peak concentration compromised hand position due to repeatedly sliding full width of stage while trying to keep playing but not collide with Patti on yacht in rough Finnish Gulf of Bothnia charts blown away by wind charts on thermal fax paper charts in wrong key charts without bar lines charts with bar lines all displaced by two beats charts in bass clef or C clef > chord charts with do/re/mi instead of C/D/E and everything else in Portuguese realization that Miles Davis, Dizzy Gillespie, Joe Pass, George Benson, Chaka Khan, Bobby McFerrin or Steve Gadd just walked in drunks falling on stage drunks disrobing on stage drunks grabbing instruments or band members band members falling asleep during song pigs frolicking in sawdust-covered frat house knocking over band equipment thinly veiled animosity between bride's and groom's families erupting into violence during heartfelt version of My Romance nightly juggling of playing and operating the lighting console/footswitches and talking to audience members and trying to reign in tempos and egos of various fellow top-40 band members arrival at duo gig with unbelievably loud, aggressive fuzz-wah hard rock bass player to discover that assignment is to back up elderly white-haired and white-suited gentleman singing unfamiliar country songs to unforgiving patrons crowded upscale happy hour dance floor unraveling into pandemonium as normal-looking customers all collapse to the floor and writhe around on each other while astonished saxophone-playing duo partner walks out leaving helpless solo guitarist playing The Hustle for 25 minutes funk bass player imprisoned in lounge band insisting on popping strings throughout sensitive ballads accidental imprisonment of Patti in wine cellar out of earshot during guitar instrumentals onstage and on-instrument living creatures with varying numbers of legs belligerent drunken bowling alley lounge customer demanding that funk band play Debussy's Clair de Lune while remainder of band looks expectantly at guitarist drummer watching ball game on portable TV with headphones throughout performance guest singer repeatedly changing keys at random moments > realization that the people who have just boldly picked up instruments and are unexpectedly sitting in are Herbie Hancock and Wah Wah Watson guns drawn at rehearsals to settle disputes about form of song marginally famous singer resorting to the dreaded "Do you know who I am" line drummer and delusional would-be front man jumping off the drums in the middle of a song and mistakenly chanting "we don't need no drummer to keep that funky beat" to a dance floor packed with suddenly hostile former dancers unstable band member deciding that it is his responsibility to educate the audience over the microphone bass player playing random notes and rhythms because he is not a bass player at all but nonetheless booked the gig drummer announcing that he killed somebody just before the show swimming pool party turning into orgy with splashing on inexperienced solo electric guitarist sitting beside pool doing his first solo gig and fielding endless requests for the same song he had just played yet again bride's and groom's special song evaporating from mortified solo musician's mind at the crucial moment band member disappearing suddenly when his chair falls backwards off riser unstable enormous man peaking on LSD brandishing artificial limb removed from his companion at audience and threatening band to "sing with this" mirrors on back wall of club causing introspective young guitarist to question meaning of his life at early stage in career.