Reducing your real estate exposure is the obvious way - if you have significantly overvalued investment properties in speculative/frothy markets, then sell up and certainly don't buy more. If you are financially overextended with your main residence, consider downsizing, or taking on a lodger to boost cashflow. If you are buying for lifestyle reasons, then get a small place acceptable for your quality of life, don't overextend on an unnecessary glamour property. If you invest, make sure you work out all the possible contingencies, including a significant price fall and vacancy periods - would this cause you merely inconvenience and paper losses, or would you be in danger of being foreclosed on and becoming a forced seller in a bear market? Is your cashflow positive and stable, or negative and insecure?
If you have been long investment real estate for a while, you will have significant profits. Consider selling some and diversifying the equity into alternative investments such as non-RE related stocks.