The question about what things you should be considering while playing an acoustic guitar really depends on how long you have been playing and how much practice you have put into your acoustic guitar playing.
Many experienced guitar players will tell you that when playing they don’t really consider anything, it’s a bit like meditation they are just into the music and everything is done on brain memory a bit like the moves of a martial arts master, they don’t have to think about blocking, kicking or punching, it becomes instinct.
When you are first starting out and for the first few years you will need to consider things like:
Keeping the melody in your head while you try and play along with it is what probably consumes most player’s thoughts when playing an acoustic guitar when they first start playing. After they have played and really know a melody it just naturally flows as subtle changes of their own improve on it until they really feel comfortable playing.
Practice makes perfect, but only if you are playing it correctly because if you are not playing correctly, then you will find the mistakes you practice, will become very hard to overcome later.
Start playing a new song very slowly and carefully until you know and feel comfortable playing it, and then speed it up to the right tempo. In this way, you will avoid learning a mistake and then having to unlearn it.
Consider being totally relaxed, sometimes this is difficult to achieve when in different circumstances and surroundings to those you’re accustomed to. You should be relaxed, especially your shoulders. Unnecessary tension will tend to hold your playing ability back and make practice as well as playing less enjoyable.
Don’t get too hung up on technique
Style and technique are a matter of individuality and largely start from the way you were originally taught and then your own interpretation from there as you learn to improvise and look for notes on the fretboard. Except when practicing, you don’t (and even then for many people while practicing) think about scales or other technical issues. You learn these so they become natural and then do them without thinking about, the music – brain – finger connection kicks in, you are just playing where your ear and ability to hold a tune takes you.
What’s important is the result and the way it makes you feel as well as any response you get from your audience.
When you first start out playing an acoustic guitar you need to think about or at least consider the way notes within a given cord are musically connected, but dwelling on them too much can cause you to get lost so in reality, you need to think less and feel more. This comes from practice and more practice, so you need to find a song you like to practice on and get it right.
Whether you’re playing an acoustic guitar or electric type of guitar most people do not have to consider too much what their fingers are doing as most of the work comes from brain fingers memory learnt through hours of practice. What you should consider is playing your version of the song.