There are, of course, several tests that hope to measure your predisposition to these functions, like on keys2cognition, which may prove helpful if you like tests as a starting point, and beyond that, you can do research on what these functions entail. Dario Nardi and Linda Berens came up with a simple chart comparing basic (passive) uses and developed (active) uses. I like it because I feel like too often, we describe the functions with their most basic uses, and it's nice to include more matured uses as well. I'll put the perceiving functions here, if it helps.
Se basic - Notice sensory data in the environment.
Se developed - Trust your instincts and take action relevant to the moment and current context.
Si basic - Recall tangible data and experiences.
Si developed - Stabilize a situation by comparing it to what is expected, known, and reliable.
Ne basic - Notice abstract patterns as they emerge.
Ne developed - Shift a situation's dynamics and explore imaginative potential possibilities.
Ni basic - Receive "ah-ha" moments and insights.
Ni developed - Pursue a greater level of awareness to transform who you are and how you think.
Remember, according to the theory, the options are Si/Ne and Ni/Se.
These are perceiving functions. So how do you perceive the world? What kind of information do you deem important (note: this can tie in with your judging function as well)? Are your perceptions focused on that which emerges from the external world (read: -e attitude preference) or do they emerge from within yourself and systems you may subconsciously have in place (read: introverted attitude preference)? Are you more interested - and I don't mean academically, I mean in your everyday life - in the concrete physical data (read: possible S preference) or in more abstract patterns (read: possible N preference)?
If you're looking for a shortcut to which function pair you use, I'm afraid I haven't found one yet