Use low pressure compressed air to remove loose particles.
For this purpose, a small amount of compressed air can be used in the spray can.
When cutting, the particles may come from the shield, or the connector itself.
Toothpicks can be used to remove small particles.
Use isopropyl alcohol on the cotton swab to clean the rest of the surface.
It is only used to complete the work because isopropyl alcohol may melt any plastic parts.
Use low pressure air again to remove residual small particles and dry the surface.
When reassembling or pairing, be careful not to distort the connector. If they are twisted, small scratches will form on the center pin, which will destroy its accuracy.
If the center pin is allowed to freely twist, the precision connector can be broken in as few as five connection/separation cycles. Small scratches can produce excessive VSWR and PIM.
Any excess flux should be cleaned because the flux is viscous and can attract contaminants. In turn, this may encourage PIM.