"I only want to improve a little,"

This may be too obvious but playing a guitar like anything is an enormously vast thing.

1 Decide what an achievable goal is that would demonstrate your small improvement
2 If you have a digital camera or a recording device record your first effort(s)
3 Work out what it is that you need to achieve your goal. I'm sure if you posted on here "I'm really struggling to work out how to do X' people would help and offer advice (I'm currently doing a similar thing in a new area of photography that I'm struggling to achieve what I want and people are enormously helpful)
4 Practice the bits that are hard rather than the bits that you already know and do well and play them S-L-O-W-L-Y until they are easier and your fingers remember them
5 At some point when you judge you are getting there (if you are really focused you might have put a time limit on it - eg someone asked me yesterday to play a song for them in a weekly session I go to. So I will learn it and play it next Monday and that's good for me to do something measurable and achievable. And I learn a new song) then repeat point #2 above and compare
6 Pat yourself on the back and smile
7 Move onto next project

I record a lot of what I do by myself and with others. Not for others but for me/us to have a benchmark rather than a perceived memory that may not quite reflect reality.

As an aside I once recorded a gig in a rock/covers band I played in. The singer knew that I did and was sure that her performance was brilliant and asked if I could send a copy. It wasn't - she was out of tune most of the night. Difficult decision... So it was the one time that my recorder malfunctioned. I don't mind being critical of me but I reckoned it would not have helped in the particular instance (rightly or wrongly)