Brass will tarnish overtime. While some people like the patina of tarnished brass, others would like to keep it polished like new. We all have different oils and PH levels that affect the jewelry that we wear. As a result brass will tarnish at different rates for different people.
There are a number of methods to clean your brass jewelry. Some people prefer to work regularly with a sunshine polishing cloth or gently brush surface with a soft brass brush, soap and water. Others prefer a variety of organic mixtures of salt and vinegar. A number of formulaes, and instructions, can be easily found on the web.
Another highly effective practice is to use commonly found cleaning agent Flitz. A trip to your local hardware store and you can find a number of brass polishers that will do an excellent job when used to manufacturers specifications.
Regardless of your choice of cleaning method, all copper based metals should be rinsed well and dried thoroughly after cleaning. Your jewelry should be stored in a dry place as brass will tarnish and become harder to clean the longer it is left damp. Oxidation is caused by exposure to oxygen so if you store your jewelry in a sealed plastic bag it slows the process.
Sterling Silver Care:
All the same cleaning and care I stated for brass jewelry applies to silver. Look for sterling silver specific polish. I highly recommend the sunshine cloth for sterling silver.
A note on ear wire handling:
The ear wires on brass hoops are the most delicate part and require finesse. Do not force opening or closing. Handle close to the closure to prevent bending the wire and putting stress on wire, soldered or riveted mechanism