First place is do google search on andoid and bidi ( bidirectional ) there is a Unicode Bidirectional logorhythm, the tricky part about Bidi is it is not al right to left, for numbers they are left to right, and any english strings displayed also need to be left to right as well.
Next thing is font rendering, especially in arabic, and small screen size, arabic fonts can be hard to read on small screens, hebrew not so much as it is more blocky.
Another point is the mirroring, western languages have left justified menus, Bidi users are used to right justified menuing. Example on Windows systems the program bar and icons are on left, for hebrew and arabic they are on the right.
Bidi is the key phrase here. ( Bi Directional) , the Android developers website has some information on bidi and that is where you should start.