OK, let's take a look at the opening bars.
The first thing that you should be aware of throughout the piece is to balance the bass movement, accompaniment, and melody. The use of rest strokes for the melody can be a very useful way to bring the melody out, but a lot of players fall foul of over accenting using this technique. Another way to approach this is to vary the volume for each part and use free strokes for the melody. For instance, in order to achieve a singing melody without over accenting, you can reduce the volume of the open B string pedal note. This has the effect of bringing out the melody without 'thwacking' out the melody and compromising the performance.
Be careful with the position shifts and be sure to let notes ring for their full value before shifting.
The use of vibrato can also be an expressive tool. Feel free to experiment as and where you feel necessary, but remember not to overdo it.