lucky is on the ball with this one. regarding his comment on the 3rd one, i totally agree. with a higher aperture setting, you will be able to achieve bokeh, which is sort of like a blurring effect on the background of the photo. i don't have the settings of the G1 in front of me, so i don't know what the maximum aperture settings on your zoom lens are.
also, i believe canon has an aperture priority mode. play around with that for a while. most of the time, i shoot in that mode with my d30 and it's pretty reliable.
as for how you can improve composition, this is something you have to practice. i know digital photography gives the impression that the photos you take are 'free'; but to truly take good photos you have to take a step back and ask yourself what you're trying to capture. else everything you take is more or less like a snapshot.
i also suggest that since it's a sunny day, you might want to invest in a UV filter. UV makes pictures more dull. you can also mess around with the photo in photoshop and take it from there. lastly, invest in a decent tripod... it will be your tool for taking good pictures everytime.