Prelude in E minor, opus 28, No. 4
Prelude in B minor, opus 28, No.6
Prelude in A major, opus 28, No.7
Prelude in C minor, opus 28, No.20
Cantabile in B-flat major
Waltz in A-minor
Largo in E flat major
These are the easiest Chopin pieces.
But some of these are better to start with than others. For example, I think you can better start with op. 28 no. 7 than with op. 28 no. 4, because op. 28 no. 4 is underestimated in difficulty. You might be able to play the piece, but to play it really well, that's hard. The left hands chords are very hard to play well.
You can start with the cantabile, largo or albumleaf, because if you ruin them it won't be that bad, since nearly nobody ever performs these pieces.