Some areas or cities are very well suited for search for investment/income property -- Long Beach is one of those areas, along with parts of San Pedro, Los Alamitos (Orange County) and certain areas of Bellflower, Lakewood. Many older areas with mixed types of housing offer opportunities.
Income property may be bought strictly on a cash flow basis for rental or investment purposes only, or it might be the way to live in one unit and rent out the other to reduce overall expenses.
Tax deductions, capital gains, depreciation, cash flow, expenses, vacancies and landlord/tenant laws are all things to consider with an income property. While many people understand they should consult their tax advisor for the first categories, many people fail to do their homework on landlord/tenant aspects of owning and renting out units. Yet it's easy to join an association which provides professional support and resources for a reasonable annual fee, so this should not be overlooked.
Long term owners of rental property are often reluctant to raise rents to the current market level, not understanding that when it's time to sell, this will hurt the market value. Whether a seller or a buyer of investment/income property, it's important to do a basic analysis to check real estate value and return on investment parameters.