One of the ways I approach playing a tune on the solo guitar is to start by establishing the chord sequence and getting that fixed in my head. Then I work out where the melody line goes on the fretboard, which is followed by playing chords or variations on chords from the sequence which underpin the melody.

Mostly I do this by ear, but sometimes I'll go back to the sheet music, if it exists - just to make sure my memory isn't at fault. (I have a sheet music archive of about 5,000 songs/tunes covering from roughly the 1880s to the late 1950s).

Having got the melody and worked out the appropriate chords or part chords, I then put the two together. This is the key process and can be very complex or very simple, depending on the tune and the approach to playing the tune. One key point I've learned over the years that complex tunes don't necessarily need full, 6-string, complex chords. Sometimes, just a pair of strings, or a moving bass string can provide enough substance to accompany the tune without running your fingers ragged!

The crucial bit - if you want to play in this style, of course - to get your fingers moving up and down freely on the fretboard, is to get to know simple inversions of basic chords. Here's an example from my YouTube videos - and I've included it, not because I recommend playing it, but because it demonstrates how a reasonably chord sequence and melody line can mesh together without too much strain:

Will FLy: The Tennessee Waltz

If anyone should want to try it, there's a free file for it here - music, tab, chords.

All this can work for traditional tunes as well as more popular stuff.