There are different factors, that influence taste:
Personal human limits: Everything that contributes to taste has a threshold, at which it becomes perceptible. Humans have different thresholds to different chemical compounds, so it may taste different to you, than to someone else.
Treating your palate right: Being able to taste subtle flavours is sometimes a matter of contrast. Regular consumption of sodas, strong coffee, super sweet stuff, etc. will make it harder to pick up subtle notes. If you really want to improve your perceptiveness you should avoid food and drinks that impart the "extremes".
Having a framework and learning: For me the major thing about "learning how to taste" is the vocabulary. It helps to describe what you taste and learning which differences two similar flavour descriptors have, helped me to learn the nuances. For example in beers most flavours are really subtle. It might be easy to find out, that a certain beer tastes like tropical fruits, but then differentiating peach, mango, lime, orange, etc. is a lot harder. It helps to have common examples of that descriptors or even the "pure thing" at hand to learn flavour descriptors.
I would say, that I've been able to taste all these things before, but I didn't had the right framework to differentiate the flavours that much.
Speaking of drinks again, for me it helps to focus on a certain aspect when having a sip: For example I focus on what flavour strikes me at first when taking a sip, then with the next sip I concentrate on how it develops, and then what the aftertaste is.