How do I overcome ageism and lack of experience?

I'm about to look for a job even though the market looks tough with a lot of people being laid off across a lot of sectors. I'm over 50 and have been out of the workforce helping care for sick family members for the last 12 years. I have a BA and MBA but also want to get into a new field. Any advice? I look young, feel hopeful, and have dreams and aspirations .. but feel I need to brace myself and be realistic. Any advice?