I don't think it's that hard. Just ask - is the S&P500 lower now than it was three months ago? If the answer is "yes" then maybe stay in cash and put that money in when the answer is "no".
Alternatively, if you want to get "fancy", you can use the 50/200 SMA crossover to determine entry and exit points. It's a much safer bet than "buy and hold" since it avoids massive drawdowns.
Alternatively, if you want to get "fancy", you can use the 50/200 SMA crossover to determine entry and exit points. It's a much safer bet than "buy and hold" since it avoids massive drawdowns.