By "have your shit together" I mean have your materials on point and ready to go. Headshot, resume, reel if you have it. Actors Access and Casting Networks updated.
If you're not in production or rehearsal, you should be in training.
Theater and film are like lions and tigers.
They can and do cross-breed, but they have wildly differing territories, practices, and cultures. Don't get butthurt when your genius at one doesn't translate to acclaim in the other.
Agents part one:
Agents only get paid on commission, period. While an agent can and will demand you have your shit together (see above), legit ones will not demand specific vendors be used. (Actor's Access and Casting Networks being the sole exceptions).
Agents part two:
Agents don't get paid for their (considerable) hard work until their clients do. Until you are at a level where you are, no bullshit, no Dunning-Kreuger, no Imposter Syndrome, consistently doing work worthy of being booked at the current going rates, don't waste an agent's time or yours.
Have a website.
Simple can do. Contact info, headshots, reel, work samples, press mentions. Platforms like Wix or Weebley can let you make a good one in minutes. Let all your social media roads lead back to that site. Other platforms come and go, but sites are still going strong after 25 years.
Have a social media presence, but don't worry about it.
If nothing else, placeholding your name so some jerk doesn't take it for a parody account is cheap hassle insurance. (and useful for the rare occasion you're asked to livetweet during an episode broadcast or come on reddit for an AmA.) One pic and your website address isn't much to put up. My insta is 90% my cats.
Make your Sm presence authentic.
Post as you (or at least the public face of you). Try not to be an asshole (unless that's the public face of you). Delicately balance the need to self-promote with the knowledge that nobody likes commercials.
Don't worry about your metrics. They're fake anyway.
There was probably a year or two where number of followers/friends/whatever influenced casting directors. Those years are gone now. In the aftermath of the 2016 election, it's become more and more clear how followers and likes can be bought by the gross lots. They don't represent actual people following you, so fewer decision makers are giving a shit. Just keep being you, and don't look to this as a shortcut.
Have a life.
Family. Friends. Make time for them now. Care about the people in your life, and spend time with them. The entertainment world builds amazing all the time, but it's all built out of glitter and bullshit. I'm no engineer, but those don't sound like sturdy building materials. Work within it, have passions for it, by all means. But make sure your life has substance in it too.
Know the difference between a contact, a colleague, a fan, and a friend.
There's nothing wrong with being one instead of another. But in an industry awash in misled intimacy, it does you good to be sure of who you open your heart to, and how wide you open it.