the resolution have no impact on the sharpness of the picture. could you upload a sample image?

are all images "dull"?

cleaning the lens inside or outside??

a dlsr works different than a compact camera - one of the main differences of the picture is the blur - or better - the bokeh (click).

what lens are you using? maybe the lens has a front- or backfocus!

you can use the fosus test chart to find out if your lens has this issue: CLICK