True, tastes of certain teas even among the connoisseurship vary. The best thing is that you already have the desire to find out, and to not add milk and sugar. This is the most important part.
As you should know, training the palate takes patience and careful dissection of tastes. I agree with Hop, taking a look at vendor's notes (albeit they're the weirdest), and fellow tea-blogger's notes can really help you to find all there is in a tea. I suggest getting as many samples, from as many different growing areas as possible.
People often use milk and sugar because they're used to their tea being bitter, and low quality. Once you dive into our high-quality, loose-leaf tea, you'll find that tea is wonderful as is. It can be sweet without sugar, and rich without cream. The real things that help here are to 1. Buy whole leaf, 2. Buy high-quality leaf, and 3. Learn how to brew it right. My suggestions for number 3 are to ask around the forums. Brewing parameters are some of the questions we answer the most. Brewing parameters are made up of a few things: leaf amount, temperature of water, brewing time, and the brewing vessel.
Here are a few:
Black: Boiling water, 3-5 minutes (5 absolute most), and leaf amount varies from person to person. I brew mine in a gaiwan, but large english pots are well-used for black tea.
Green: Under 180°f water, under 2 minutes, and about 1 tsp to 3-5oz water. There are so many different kinds of green tea, so its hard to give advice here. The parameters above are best for Japanese green tea, but can also be applied to most greens. Chinese greens, however, like lower water temperatures.
That's a good start, let us knwo if you have any more questions.