I have a super simple craft to update any top (or to rescue a sweater with a stain - which never happens to me).
I don't have detailed photos, but this one is pretty easy.
I cut out a few flowers from a pillowcase I got from GW (Goodwill). Used a little Stitch Witchery & simply sandwiched the Stitch Witchery between the cut outs & the sweater, ironed them down & then stitched them down. I used a sewing machine to sew the appliques on, but you could easily hand sew it too. I left the edges raw so they would fray a little in the wash (It must have been a high thread count, because the fraying has been minimal).
Then I gathered up a few seed beads, hand sewed them in the centers of the flowers & a few on the petals. You could use rhinestones or sequins & glue if you weren't in the mood for needle & thread.