PSP DISASSEMBLY/ SPEAKER REPLACEMENT Help me PLEASE.

[Dinesy]

Right, as i need to repair my PSP's speakers, i was wondering how to stop dust gathering under the face plate when you reassemble the PSP..
Because when i modded my old PSP 2000, there is alot of dust under the faceplate and on the internal screen...

Basically, how do you create a dust free environment ? Or just stop the dust gathering on the PSP internal screen and inside the faceplate, this PSP is in mint condition, i dont want to spoil the screen with stupid dust marks etc...

How do i stop this from happening ? 

If you have any idea, please just help me. 

Thanks in advance