you should join a camera club, that way you'll learn even more plus you get photos assessed by judges which always helps. for example the first pic, the boat, the image has a top and bottom half as you've got the horizon straight across the middle of the image. that's something to avoid. the sun is burned out in the top half plus the rocks? in the foreground are too dark. i'd be tempted to crop out these two things and experiment a little with this. what is nice about the image is the tone and the waves plus you do have a boat in the image-was this added later or did the boat just happen to come along?
anyway that's the sort of thing you learn at camera clubs plus you get to see other folks images which is good for inspiration! i've got the 450d too and thinks its a great camera plus i also use photoshop too help with images.