Hand and card photo of my own.

Roses used for the background.

Heart brushes of my own design

Lips photo by clarita

First, the source photo was duplicated, then the background texture was cloned to cover the letterbox completely. This textured surface will come through the next layer.

The roses are moved over the cloned, textured background.

Rose layer now is lowered in opacity setting (on layer window) to allow textures to show through. (63% is what I used, but this is your choice.)

Here lips were duplicated, rotated, and scaled to varying sizes, added to background, and opacity lowered. Later, however, I decided to just use lips on the letter being mailed, so deleted the rest.

Letter box is now lassoed from source photo, then chopped and moved onto canvas. It is duplicated twice to be scaled to slightly different sizes, then color changed with hue/saturation tool.

Hand and card are chopped and placed onto canvas.

Hearts are inserted using the brush tool (left side only)
where they will be scaled to different sizes (edit/transform/scale tool), then embossed and beveled. Colors are also changed with hue/saturation tool.

Heart settings for their shadows and shapes are set on Layer/shadows/bevel with these percentages:
Inner Bevel
Smooth
Depth 231%
Up
Size 21 px
Soften 0 px
Angle 51
Alt 0
HIghlights Opacity 75%
Shadow Opacity 75 %

Cards for the boxes are created from the corner of the card already inserted. Duplicate it, cut off corner, resize and rotate it, and change hue to insert into boxes. Trim off overlap to fit shape of boxes. (I lower opacity of the letters in order to see where they overlap, use eraser tool to shape to box, then bring opacity back up. Boxes also are beveled and shadowed as with the hearts.

After all fine tunings are done, visible layers are merged then a violet layer overlay is added. The opacity of this layer is set at 25% to keep it from looking too purplish. After saving this final layer, I go 'backwards' until getting back to the place right before the merge, so that if any final changes have to be made, the individual layers will still be available.