if you want sharper, better photos, get the tamron 17-50mm f/2.8 lens. I got mine for $350 used and it's been worth every penny. You just won't believe what better glass will do for your photography until you pony up.
For right now, use ISO100 and f/8. Practice being as steady as a sniper when you click the shutter. Use a tripod if you need to. Remember to set yourself up (IE camera settings, posture, framing, etc) for EVERY shot. Really think about and see what you want this photo to look like before you even look through the view finder. Then make your camera capture the scene exactly how you see it.
It's amazing how, even at the fastest shutter speeds and the widest angles, the stiller you can hold the camera, the better.
Anyway, keep practicing the basics until you can afford better equipment. Everyone here will probably tell you that your equipment is not your limiting factor, and you should keep learning with your base level stuff until better equipment will make the difference, but I can tell you that shooting with nice stuff is just better. You'll "oops" into some really great shots, and learn how to make your skills meet up with the quality of your gear.
At least that's how I feel.
Good luck and keep learning and always keep an open mind!