New player with a few questions.

[Anova]

As above, you need to decide whether you want to run as a healer or dps. If you're unsure which one is the best fit for you, just remember you can freely change between the jobs at any time. Also, on the plus side, when you level arcanist, you also level both the scholar and summoner jobs. You still have to collect weapon and armor sets for both roles (since one is a healer and one is a caster, you will need to keep 2 sets of armor and weapons starting from lv.50+), but it's something you can keep in mind if you want options. If you have any specific questions or concerns about the jobs, feel free to ask below.

As mentioned before: you will want to get your thaumaturge, conjurer, and archer to lv.26 and 34 respectively, for all the necessary skills at end-game. However, for now, simply get your Archer and Conjurer to lv.15 so you can class change. You can do this very easily by doing the 1st hunting log for your classes, any FATEs along the way (approximately 3-5 FATEs), and your lv5 to 15 guildhests (you get the bonus exp the first time you do a guildhest with the class, for all classes). It's not a terrible grind as they all teach you the basics for playing and introduce you to unique mechanics (such as your rotation for THM and strafing/kiting for ARC).

FF14 has this tendency to start players off very simply and to introduce its core mechanics early on. Get in the practice of using Aetherflow as soon as it's up. If you're not using all the charges now, that's fine. Starting from lv.40 on, you'll get more abilities that use the charges. Aetherflow is a very necessary and important resource for you to manage at later levels, so it's fine if you're still learning to conserve the charges at lv.30. Trust me when I say you will soon wish for more charges.

If I were to explain its importance: Scholars use it to use their most powerful healing abilities, whereas summoners use it for their most powerful damage abilities. In other words, Aetherflow is directly linked to your ability to burst heal and burst damage as a Scholar/Summoner. Keep it up always, and try to maximize the most out of it. As a general rule of thumb: think tactically and strategically with Aetherflow. It's a resource that resets every 60 seconds (or about once for every mob group). Try to decrease the time each encounter takes. This can be done with bane to spread your dot damage to multiple enemies at once (providing you with very good aoe damage), you can use drain for a small amount of burst damage, or (as summoner) use it to inflict massive burst damage on a single, troublesome/priority target you've inflicted with your dots. Alternatively, as a Scholar, use it to perform massive heals instantly. The most common use of this for scholars is that they can spend more time in cleric stance doing damage, letting the tank drop down to low hp, before needing to switch out of cleric and using their aetherflow to heal the tank to full (or to perform an emergency heal because someone didn't dodge a telegraphed aoe).

Welcome to the game and hope to see you at lv.50 or higher soon!