How to learn the powerful words, that usually gets the attention of readers first?
First, you need to identify what you personally consider "powerful" words, or poems, or sentences in fiction. Make a collection of the things you love.
Once you have a collection of what impresses you, or moves you, then you can move on to analysis: Try to understand why exactly you feel like the authors found the perfect word, the perfect imagery. Is there a surprise in it, something that startles the reader, some word or phrase or juxtaposition if images that made a new connection for you?
Before you can do something on purpose, you need to understand what works and why. You can't just memorize rules of grammar or rhythm or rhyme. Rules will help, they will let you write something that is needed a sonnet or haiku or Acrostic, but they aren't enough to stir emotions in people, which is the purpose of poetry.
To stir emotion, you need to connect imagery and particular words with emotion. Different words carry different emotions; "heart" and "green" are examples. Some imagery invokes different emotion, there is a difference in feeling between "rowing at night on a sleepy sea" and "rowing quietly across the ripples of blue".
Collect what you love. Figure out how to sort it into categories. Figure out what the categories have in common. Understand why certain words, phrases and constructions work for you, so you can apply the rules YOU discover and develop to your own poetry.
Your question indicates that you are a long way away. Poetry, the poetic, is not about power words (they are for sales and speeches). A lot of classical poetry is about the ambiguity and latitude of language.
"He kissed me in such a pretty way."
- No power words here but can you see that a normally visual attribute has be a feeling.
"I wandered lonely as a cloud."
- Again, nice words but almost nonsensical, certainly not powerful. Clouds do not wander. Their direction is dictated by the wind. Clouds are rarely lonely. You rarely see a single cloud.
Poetry is about breadth of language, not power.