What if I can’t make up my mind on the direction (bullish/bearish/neutral) of the underlying?

First of all, remember that you can get the direction wrong and STILL be profitable on a credit spread trade. As long as the underlying doesn't go past your short strike, you're still profitable. It can even go slightly past your short strike before you start losing money (because the credit you collect gives you some cushion). 

But at the end of the day, if you're not sure, just skip the trade! Or place the trade in your simulation trading account to see how it plays out. It's important to learn how to trust your intuition as a trader, and the only way to do that is with experience.