I brought this to the meeting yesterday...
LEGO Tree in Blossom by James Shields, on Flickr
Cherry blossom tree built mostly with flower pieces. The main technique is to keep the flower petals on their sprues, connected my stem pieces.
A run down of the method follows...
1. First attach stalks to each corner of the flower sprue.
2. Next, attach to the foliage piece, and keep adding more flower sprues.
3. Add further flower pieces. Connect to the foliage where you can, but it doesn't matter if stems are only connected to flower sprues.
4. Keep going past the edges so that flower sprues hang down on floating stems.
5. The completed section from underneath.
6. Next, attach a plate with vertical bar (or any part with a bar for a strong connection to the foliage) to your tree branch.
7. ...which should be attached to your tree...
8. Push the bar of the plate into one of the holes of the foliage.