I mainly just clean my speaker grills by just stroking over them with a fine soft artists paintbrush. Seems to do a nice job of removing dust particles and dirt.
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Phone: HTC ONE (M8)
Firmware: 1.54.401.10 - Rooted
Phone: HTC ONE
Phone: HTC ONE X (International Tegra 3 Variation)
PHONE: HTC Sensation
PHONE: EU HTC HD2 (512 Mb)