Hifz or Memorization is necessary for a Qari, because you can be a great reciter but if you have nothing to read, what's the use? Being a Hafiz and being a Qari are not mutually exclusive meaning you can be a Qari and not a Hafiz or a Hafiz and not a Qari. In our app, we denote if the individual is a hafiz with an emblem next to his name and a note to the side. Hifz should run parallel to all other Quran studies, you can be reading a page or so a day, but put aside a fixed time to Memorize! Also revise what you have memorized, and test yourself by covering the page and with others too. We're in the development of an Android/iOS app that will track and gamify Quran Memorization to incentivise students but for now it's up to you to maintain your schedule.
There are, at most, 3 stories with every passage of the Quran: The story Allah(swt) tells, the story of what's going on in the life of the Prophet(saw) when the verses are revealed and the story of what it means to you. Certian Surahs contain narratives like surah Yusuf, Maryam, Qasas, Kahf, etc. where the ayahs follow a logical progression. These are typically the easiest to memorize after the ones from the 28th, 29th and 30th juz. The next group regards things that happened in the prophet's lifetime like surah Israa, Mumtahina, Hashr, Noor, where knowing the Seerah (history) really helps. For this I recommend watching the Umar series where episode 1 is linked below. The last group is where certian surahs have a relative importance to you, e.g. I memorized surah Qaf easily because my brother is named Muneeb or certian ayahs in Zumar related to me when I was depressed. Once you know the meanings of what you recite and create mnemonics, it's easier to memorize.
Like Tajweed, you can't memorize Quran all by yourself without testing yourself or having others test you periodically. This is the feedback mechanism to getting better with your memory. Sometimes you might make a mistake and compound it with others if you're not corrected and it'll make you go back an change what you already committed to memory. Luckily we have Qari Corner to help connect you to people who can test your memory and inshAllah as you grow, Allah(swt) will reward you for your efforts. You can then leverage your understanding to teach others.