I've been thinking about doing a proper WordPress blog post about this but since my executive functioning hasn't come back from the war for that level of Formality (TM), let's do this, instead.
Basic skills I wish I'd been encouraged to start with as a baby polytheist spiritworker.
My teen nephew has been making noises about learning spiritwork, so here's what I basically told him.
Have a mindfulness practice so that you know where 'you' end and 'other' begins.
The difference may not be so straightforward, depending on a whole variety of spiritual factors, but GENERALLY SPEAKING, you want to have a baseline standard of being able to know what's your internal narrator/intrusive thoughts/mental illness/etc and what's actually other entities. Not all (or even most) random thoughts for most people are actual spirit chatter. Work on your discernment.
If possible, I'd recommend having a supportive but critical third-party support: a therapist you actually trust, for example. Especially in the beginning, it's easy to get sucked into thinking everything is spirit contact, or spiritual damage, or spiritual something. Maybe it is! A lot of it isn't. Having an incredulous (but supportive) sounding board can help you calibrate how your personal brain stuff plays with your spiritual stuff, and also help avoid getting sucked into cultish movements that do harmful stuff like equate trauma = empathic psychicness.
Additionally, if you're familiar with your spiritual body, e.g. how your physical body carries spiritual energy, it can also help you know when you've picked up unwanted Stuff like some curses, spiritual parasites, or other immaterial 'gunk.'
"Mindfulness" can look a bunch of different ways. More conventional mods of meditation are perfectly fine, but other kinds of somatic/embodiment practices can work just as well: experiment to see what's compatible and sustainable for your lifestyle, resources, and cognitive processing style.
Pick an external divination style and get comfortable with it.
Doesn't really matter what kind: what you're looking for is some kind of a system that can become a shared language between you and your own spirits/gods/blessed powers. That can take some negotiation, and you can always change systems, but pick one to start with and get to know it.
You won't always have to rely on another person to act as the messenger between you and your own spirits. (That said, there are times when you shouldn't do your own div, but that's a different post.)
Having an external div option will help you double-check on your own intuition. Not sure if what you saw was a sign from your spirits? Use div to make a more formal check. If we're personally invested in a particular answer to a question we have, that can skew how we interpret our intuition.
Helps deepen personal relationship between you and your spirits, which also makes shit like mediumship or using omens easier.
You can double-check other people's divination for you. For more important/higher stakes stuff (such as a Tarot reader telling you that a specific deity is now claiming you and you have to swear an oath, dear lord, please take don't take that as face value without at least a second opinion!), this can be particularly important in terms of maintaining a sense of autonomy over your own relationships with your blessed powers.
Basic healthy communication skills that frankly most of us aren't ever taught.
All the meditation and div practice in the world isn't gonna do shit if you don't know how to talk to other beings, human or otherwise. You know what made the actual biggest difference for me in transitioning from 'flailing baby pagan practice' to 'devotional polytheist priest'?
Knowing my boundaries AND how to negotiate them safely and healthily. Learning how to do possessory mediumship first started with me getting every single one of my trauma triggers slammed ALL AT ONCE. Nothing healthy would've come out of that experience if I hadn't had been intentionally practicing my boundary-setting skills in my mundane human relationships, AND if my blessed powers hadn't been willing to meet me halfway. It took a LOT of conversation and mistakes were made on both sides, but now possession is something that's become privately sacred and beautiful and wonderful for me, partially because of how hard-earned it was and how it required the development of mutual trust. (Now I get scolded for being TOO trusting with my main lady, oops. 😅)
Conflict management. A lot of people are conflict-avoidant. That's not helpful. It's also not helpful if you dread 'getting in trouble' or 'being a disappointment' every time you have contact with your blessed powers. Learn how to handle disagreement, misunderstandings, disappointment, and frustration with more intention and skill so that you can move past those inevitable incidents with growth instead of deeper shame, resentment, or resignation.
Assertive communication (or your social/cultural equivalent of that, since what's considered 'appropriate communication' might change based on culture, circumstances, etc). Assertive isn't the same as aggressive, either. But basically, this is the kind of communication that's like, "What are your needs, and what are my needs, and how can we collaborate on exploring options to get both our needs met with mutual respect and dignity?" For example: when my blessed powers ask for a daily disciplined routine, my ADHD ass has learned to ask what the goal is and here are the methods I am neurologically capable of to achieve said goals, how does that sound? So far, we've always been able to come to a mutually satisfying plan that doesn't deepen my old, unhelpful, internalized ableist narrative of being 'too broken to do something that any neurotypical person could do.'
There are lots of other helpful skills, both spiritual and mundane, and not everyone may agree with the ones I picked out here, but these are the most basic ones I find myself returning to most often and being the most thankful for, personally.