Think of a guitar (or any stringed instrument) string as sort of like a rubber band thatâs lost itâs elastic mo-jo. Over time, strings get stretched to their limit from constant tuning and playing. They also become oxidized by the natural skin oils and soil from fingers, and from exposure to air, which erodes heir tensile quality. Worn strings lose their brilliance, make it harder to keep the guitar in tune and may cause buzz. Wiping the strings down with a clean, dry, lint free cloth (I cut up an old pillow case into manageable pieces and keep them handy) after each playing session helps-a lot. I give the back of the neck a couple of swipes to. Youâd be surprised at what youâll find accumulating on that cloth over time.
Climate, playing style and frequency should also be considered - hard attack players who play alot may find the need to change strings more often compared to soft strummers - but eventually, nature will prevail. I have multiple guitars, so no one guitar gets played all the time. Still, I check them often and change out at least once a year.
Iâve found that keeping strings clean, serviceable and fresh to be one of the most cost effective ways of keeping my guitar sounding and playing the best it can. As for sorting out the seemingly endless choices to fit your personal playing preference, wellâŚyouâre on your own there 
!
Hope this helps!
PG
My classical and steel both have just settled in to needing very little tuning now. The strings sound great. I suspect they will need to be replaced soonâŚ
I think I agree with @jkahn. At this level of play, late beginner for me, and averaging 1 or 1.5 hrs play most days, the stings probably last a pretty long and very hard to determine time and our needs for perfection may be a bit less than in the future.
I will change them when I feel like it.
Just added a song that requires E flat tuning (all strings lowered one semitone) to my practice, so that means I will be tuning my strings up and down every day. Is that going to shorten the lifespan of the strings?
Not that it really makes much difference, Iâm still going to have to retune up and down every day, but I might be more proactive about replacing strings if I know they are wearing faster.
Nope, I retune quite a bit and itâs fine. Main thing that would affect lifespan of strings are type of string and how much you play. The first strings on my strat were dead before two months (Ernie ball I would assume), Elixirs have been on for ages and still sound good. Probably about 10 months.
If you know youâll practice this song every day for, say, a week, then why donât you leave the guitar tuned to Eb and just put a capo on the 1st fret for your other practice items?
Interesting idea Jozsef. I hadnât thought of that but it makes sense. I guess my only concern would be for PFC training, I want to be encoding that muscle memory against the fret spacing on standard E tuning.
I realized that in my guitar learning journey, Iâve neglected to consider a most critical element - choice of strings! How could this be? Back in the day, there were not so many choices so it was pretty easy to choose, so in my âborn-againâ guitar life, I defaulted to my old go-toâs without a thought ( Ernie Ball 10âs) - for everything! I was still in the âguitar string 60âsâ and ignorant of the advances in design and manufacture. New materials, alloys, production methods, coatings etc have really changed everything, but made choosing difficult and confusing. Round wound/ flat wound, coated/uncoated, etc. So rather than berate myself for this oversight any more than necessary, I decided to delve into the world of guitar strings. I came across this most excellent article that discusses and compares the differences between the various types and many leading brands of strings. It also covers application, care, expected lifespan; tips on noticing wear and when to change them out, proper winding, etc. I hope that others may find it useful. 
How timely, @Papa_G, thank you for sharing this! Iâve promised myself to learn to change my strings, and planned to search the Community tonight to help me decide what strings to get. I was aware of gauge, and vaguely that there are different matrials, but had no idea there was so much to know!
@judi
Glad you found it useful! Yes, it seems as thought they are a world unto themselves and canât believe that I didnât recognize their importance sooner. Maybe itâs because guitars are (arguably) the most familiar instrument - that is, found in so many homes (closets? 
). I think that learning to do my own set-ups has led to a new understanding of, and respect for, guitars - regardless of build quality; How each component relates to others, and how proper settings directly impact play-ability, tuning and sound in large and small ways cannot be overstated.
Anyway,I finally settled on dâaddario Phosphor-Bronze custom lights for my acoustics.Their dynamic range, warm brilliance and easy play-ability are a good fit for me and make for a very gratifying playing experience. I still have a few back-up sets of Ernie Ball 10âs for my electrics, but I think Iâll start to experiment a little when it comes time to change them out. Iâm open to suggestions if anyone has them. In the meantime, I have to think about what else I might be missing⌠
Take care!
It looks great! My first two builds have been Stewmac kits, a 000 and a 1933 OM-18. It is definitely a lot of work, but I found that I love doing it. Of course being retired and having the time helps a LOT. 