Staining cells for F-actin with fluorescently labeled phalloidin

Wash coverslip 1x with PBS.
Fix 10 min with 3.7% formaldehyde.
Wash 1x with PBS.
Permeabilize with 0.1% Triton X-100/PBS.
Add TRITC-phalloidin or FITC-phalloidin (or phalloidin conjugated to fluorophore of choice). For rhodamine-phalloidin from Molecular Probes, ~50 - 200 nM final works well.
Wash 2x with PBS.
Remove PBS.
Tamp side of coverslip carefully on Kimwipe to soak off remaining PBS.
Add mounting media.
Mount on slide.
Use fingernail polish to seal side.