With so much in life, it is about personal opinion, what you believe states one message, another individual will believe it says something else.
The colours and techniques used may make a picture fantastic in your eyes but not in another’s.
In short, what makes a good or best picture? There is no formula, the whole result is dependent upon those who view it.
Therefore do not believe that the last picture you shot is not very good, it probably is, but just not to you. It is very common to take tens, even hundreds of shots until you get the one you like.
Have you ever stopped to think that when you are at sporting/public events why there are so many cameramen taking lots of pictures when only a handful make it to the front pages of newspapers? This is because they are taking lots to get what they believe is the best photo for the job – they may well take 100 to get 1 publishable photo, but they took the 100 to get to that 1 photo.
Add to this now that fact that digital memory and storage space is so cheap, you can easily store hundreds, thousands, even millions of pictures if you wanted for relatively low costs. Do not be afraid to keep pictures, they work as a log/journal of your work and are always good to look back on, they are a photo a memory.