I am a 32 year old guitar player so I will try to add some perspectives.. I agree with some replies, with a few I don't.. If you want gigs learn bass.. I suggest electric bass as standup is more blugrass and jazz.. Depends on what you want to do, as you get older you might need to get more hours in then someone younger, so you might need to play 300 hours to be where a younger kid might get by 270 hours, but it is all personnel too. If you have experience with other instruments, big plus.. Eventually you will have more than enough technique, the rest is all knowledge (songs, scales, being able to hear and recognize progressions in your head...) Another words, auditory visualization.. I play jazz amongst other musics so in 20 years of playing I've had years that had me play 5 hours a day, have had 2 month spurts of 12 hours a day, and getting some 12 hour days in each month with atleast 2-5 hours each day is pretty essential to a musican (performing..) many of my heroes play 8 hours a day everyday, no vacation or breaks.. Now if you just want to play some songs and have fun, I suggest 2 hours a day, but at least one hour every day with a metronome, Also pract, ice variety, some scales, some chords, some rhythm, some stretches that hurt after a few minutes... make goals.. 2 hours a day is not enough to ever become a master, but enough to learn and do well enough to play rock, country, blues tunes and even jam with a shredder who will do all the complex stuff.. Listening is the most important skill.. Some cats have mad chops and don't know what to play when, if you only play single notes but always play the perfect note, you would still be the better jammer.. So outside of all the physical stuff, it is the mental understanding and visualization that will give you the most... As much as I practice, I had faster scales at 21 then now at 32, but I can play complex ideas now that I could have never done at 21, because then it was all stamina and fire, now it is refinement and knowledge.. let me restate that, I could play fast forever back then, now I get tired if I play 64th notes for an hour straight, but I never need to in a musical setting, and can skip across ideas and have focus and development which I was lacking at 21.. so it is all mental after you get the physical down.. Also, guitar or piano are best suited if you want to play songs by yourself, after that mandolin.. Don't pick up a brass instrument unless you expect to be playing with people a lot, monotonal instruments are great, and I love sax players, but the sax players I listen to are monsters who can always get gig with a bassist and piano... If you are only playing an hour a day, guitar can make chords etc... Violin, Sax, Trumpet are great instruments if you play with someone else, or you are a master.. but then it will take 10 hours a day for a long time before you can entertain (and blow away) people by playing sax by yourself... And the masters like Sonny Rollins will out play even Eddie Van Halen solo, sax vs guitar... but if you are a enthused amatuer.. stick to guitar..