A shallow depth of field doesn't necessarily make for a good photo.
First things first, remove the border on the top photo - black borders commonly isolate a photograph/piece of art, as the negative space created is incredibly distinct. Secondly, in terms of signatures or watermarks, making a watermark that is more of a logoform rather than plain text can be far more effective, especially seeing as it can be made smaller (yet still recognisable). Work on some sort of logoform, closer in size to a square (or a rectangle of the golden ratio), as these generally tend to be the norm. Lastly in terms of basics, work on placement of the logo. The bottom right isn't always a suitable place for it - it needs to compliment the composition of the photo itself, and as seen in the second photograph, the type heavily weighs the composition onto the right side of the piece (along with the second foot in the background).
With the actual photographs themselves, the perspective on the first is odd - the shadow stemming from the flash is distracting, and can be removed by shielding the flash by a piece of paper etc.
The second seems tilted, due to the shape at the bottom of the photo being uneven with the margins themselves.
Work on composition, and read up about rules of photography; it'll actually help.
