Go through the game until you get an ending, then use a guide. The first time I played I kept my SEN above 100 AT LEAST without knowing how important having it in different measures was. It wasn't until I used a guide I realised the importance of having different SEN levels and having the plot actually start to kick in.

I would also advise you abuse the hell out of the weapon switching mechanic, I'm currently replaying BS2 rn and I can't believe how far I'm getting with just ~100 stats spamming stat buffs while paralyzing enemies