I am working on BlackBerry user interface. But the BlackBerry UIs are less attractive compared to Android UI. I want to make my BlackBerry UI more attractive like in Android.
Well, after a couple of beers a lot of things look more attractive... ;-)
But seriously, I think you're going to run into some fundamental limitations with the platform you have. The iPhone, Pre, and (I guess?) the Android all have dedicated graphics hardware which can antialias text and perform complex animations with relative ease. Most blackberries don't.
I generally suggest to people that when they do a design, that they try to stay within the boundaries of the device they're designing for. For example, if you're writing an app for Windows XP, don't try to make it look like it might on a Mac. Stay with the style of the best-of-breed applications on the particular platform you're designing for. Maybe this answer isn't helpful, I don't know... But it was a pretty general question.
@Dave Markle is right, this is a fairly general question. Assuming that by 'attractive' you mean 'UI Controls that look better than the default' then you'll have to do a lot of custom control work. More an more in the BlackBerry industry it seems that leading applications are doing almost entirely custom UIs.
I won't touch on specifics of graphic design, that seems outside the scope of SO, but a good place to start is to get a graphics designer to put together some conceptual screens, and then as a developer your job will be to build controls to match that.
There are some tutorials on the net about how to get started with that. I've written a few - "BlackBerry UI - A simple custom field" is a good basic introduction on how to make a custom control.
And a correction to @Dave's comment - you can antialias text on the BlackBerry - though it's not well documented. For example, a 9 pt subpixel antialiased bold font, derived from the default system font:
Font.getDefault().derive(Font.BOLD, 9 Ui.UNITS_pt, Font.ANTIALIAS_SUBPIXEL, 0);