With practice all your technical skills like modeling and unwrapping will improve.  Regradless of your current technical skill level start developing an eye for detail as this will greatly improve the final rendered image.  Look at the details that make real world objects look real.  It is usually the imperfections that are important and the texturing is where these are best added.  Damage, dirt and grunge, cracks and scratches, stains etc. are all important details that add to realisim in the texturing.  

One of the most important rules in texturing is to avoid repetition or tiling textures on a surface that could not possible have that occur.  Looking at your barrel each plank has the same weathered wood texture applied.  The human brain is wired for pattern recognition.  Look at clouds or inkblots and the brain will attempt to seek out a pattern from randomness.  Repeating textures on a model is one of the first things the eye will notice.  Also no texture at all where there should be some detail jumps out as well.  The metal bands holding the barrel together should have detail such as dirt, rust, scratches. 

For modeling and texturing get into the habit of looking for reference pictures.  These will assist greatly in giving you a guide as to the level of texturing detail that you need to "sell" the image.   

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