I've used a similar tie top as a template, they are quite straight forward, yet really effective.
*Cut to appropriate size, with two long strips as ties at the front
*Serge (overlock) all raw edges
*Sew two sides together, from armpit to bottom side, before tie.
*Fold under and stitch serged armholes, back, and ties.
I've also restyled this pink and white floral top, by cropping, removing both sleeves, and adding darts for a better fit.
(notice the cat leg!)
Adding a dart
Lots more of these to come, I'll try to document more detailed 'how-to's next time.