Always use cleaners specifically designed for the precious metal contacts used in low current applications found in high-tech electronics. The low current makes the contacts exceptionally sensitive to contamination, yet their ultra thin precious metal plating is easy to damage during cleaning.
Never use the cleaners commonly associated with SCUBA maintenance. Many such cleaners contain solvents that are polar and may also leave residues, making them a potential problem in low current applications. This is also true of many household products such as rubbing alcohol.
Never use ordinary 'tuner cleaner' products for cleaning precious metal contacts, particularly with rebreathers. Their cleaning action is too harsh and most formulations sold by consumer electronics retailers contain petroleum distillates, which are flammable and not safe for use with some plastics.
Never use silicone based cleaner/lubricants with electrical contacts, even though this is an often suggested practice. Silicone products will react with plastics and other contaminates to form insulating films and silicone carbide compounds which can cause intermittent connections.
Never use a pencil eraser to clean precious metal contacts, even though this is another common practice. Erasers are highly abrasive and will remove the ultra thin precious metal plating. Further, the glue in erasers leaves behind a film that is extremely difficult to remove and can also cause intermittent connections.