I don't know if this applys to your specific needs, but if you are manipulating the texture such as filling in adjacent areas, rotating etc. Try working at the highest resolution your machine can handle and at 16 bit. This will maintain as much data as possible. Avoid cloning as much as possible, instead copy and paste the area you want to expand and use the erase tool to blend with the underlying layer if needed. The healing brush works well for small areas. Anytime you manipulate pixels in any way you degrade them to a certain extent. If you you need to resize an area use the measure tool to determine the finished size you need and resample the texture area as opposed to using the scale or transform tool. When the entire map is finished resample it back down to the size you want and convert back to 8 bit. Bump maps will certainly help to define a texture. Another technique I use that seems to make textures really pop out is to place a duplicate map that has been treated with the color photo filter of your choosing and you might try adjusting levels of this secondary map. Place this map into the translucent node and experiment with different percentages between the diffuse and translucent map.
Chris