What kind of equipment are you using? If you're shooting film, what kind? If digital, what kind (brand and MP). I'm asking because they're decent shots, but the colors seem a little "washed out" to me which is generally caused by "cheap" color film and/or wrong speed/ISO. Similar for digital, low MP and/or wrong ISO. If you're using an SLR (film or digital), I'd strongly recommend shooting in manual mode.. it gives you full control over shutter speed, aperture, etc.. Take multiple shots of the same scene using different settings, note them, and then see which you like best.
It all boils down to practice, practice, practice =)