Tips/Advice for a Playthrough of Pokemon X/Y?

Question

A thread for posting (spoiler-free) advice for a playthrough of the given game which will help anyone playing it. The aim of this thread is to make playthroughs easier for someone who is playing it for the first time.

A couple of rules:

1. Don't give advice for Pokemon as a whole. Seperate thread for that can be found here.
2. Try to keep advice beginner friendly. Do not go into the more complex mechanics.
3. Don't post multiple answers. Edit your existing answers to add more.
4. No repetition

Comments

pokemon X/Y are some of the best games ever in my opinion!
I just jumped in headfirst and absolutely loved them. so I say just play it how u want to!

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How is this unanswered? All the XY questions are usually flooded with answers.

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It's probably because most XY questions were answered around the time when XY released