Experience. Notice. Investigate. Revise. Repeat.
Notice that there is no final resting point. There is no state in which you become the perfect observer. There is no state in which you finally understand yourself and feel enlightened. Every new encounter provides more evidence. Every mistaken prediction improves the model of reality if you are willing to revise it.
We do not possess reality but "orbit as close as possible around its heart." This captures your contact with realisty beautifully. The task is not enlightenment but orbital correction. Every conversation, every disappointment, every scientific discovery, every book, every bodily reaction, every relationship slightly adjusts the trajectory. Some adjustments bring us closer to the underlying structure of things. Others carry us away.
Spinozist life is not a life of detached observation but a life of disciplined participation. You do not leave reality in order to sit down to observe and understand it. You enter it as fully as you can, while continuously asking one question that the ego dislikes because it threatens certainty.
"What is actually causing this?"
That question is never passive. It is the beginning of both understanding and action. It does not ask you to surrender to reality or to dominate it. It asks you to know it well enough that your actions become responses to what is there rather than reactions to what you imagined should have been. Hopefully, that is much closer to Spinoza than the image of a serene observer sitting outside the stream of life. Spinoza's philosopher is not outside the river. They are in the current, trying to understand its flow while they themselves are being carried by it.
In fact, this mental activity is so common that we all do it sometimes, just not fully aware of it. And we don't need gurus with fancy techniques, which usually boil down to observation and analysis, and otherwise, something important is missed.