It turned my whole year around to find my own answers to those same questions -- I've learned I'm long biased so every chart looks like its going up even the ones that are just the inverse of whatever I'm looking at lol.  I use Matt's $NAHL indicator and add that COMPQ has to close > 0 three days in a row AND SPX has to close > 200 DMA. That's my checklist. Until/unless that happens, its the "bear market playbook" for me:

1) Look primarily for mean reversion trades instead of trend following (like the  systems do)

2) Take profits aggressively instead of letting things run

3) Keep a large cash position and stay hedged/market neutral most of the time.

Also I chose 3 days in a row bc Matt has mentioned it can close > 0 1-2 days in a row during a bear market, so 3 should be more meaningful -- its also not a buy signal, just a mindset change for me, the bull market playbook is basically the opposite of the bear. 

Would be really interesting to hear what strategies are working for other others right now.