Arranging piano music for guitar is a minefield: the vastly larger range of the piano, it's favoured soprano rather than tenor melody tessitura and the sheer number of notes & ability to play many voiced complex counterpoint all militate against making convincing transcriptions for the guitar.
If you are determined to try it, start by analysing well known & accepted transcriptions. Albeniz' Suite Española has the famous Asturias / Leyenda, Granada, Sevilla & others often transcribed for the guitar. Once analysed you will notice that keys are often changed, the range is usually compressed by for example dropping the melody down an octave / leaving out the upper notes of octave melodies, the chords are thinned out / inner voices re-arranged etc etc.
Suite Española pieces mostly work well because of their appropriate Spanish flavour & clear simple melodies & harmonies. In contrast Albeniz' Iberia suite is impossible on solo guitar because of its virtuosic nature.
There are undoubtedly more poor arrangements of piano music than good ones so frankly I would tread carefully. A few of the simplest Baroque keyboard pieces can work relatively well but often these take too many liberties.
Frustratingly, some keyboard pieces look as if they should work on guitar, but on closer inspection don't. One example is Bach's 1st C Major prelude from the WTC (BWV 846, 1) which is often attempted on guitar but primarily fails on our instrument because (again) the original range is far too wide and because it is impossible to sustain some of the arpeggio notes in some of the chords in the way the composer intended.
A more realistic prospect is to arrange a piano piece as a guitar duet although even then keys will often need to be changed & some range compromises will be needed (sticking some non-melodic bass notes up an octave etc). Bach's 2 part inventions or simpler pieces from the Anna Magdalena book might be a good start.