I was really interested in playing this game after reading about it, but I have almost no experience when it comes to text-based, other than the occasional Dwarf Fortress. What are some basics I need to know before playing this game?
SD was my first MUD as well, and there really can't be any advice for it beyond jump in feet first. It's a MASSIVE learning curve, but after you get over it and start figuring out how to do things, it gets easier and more fun.
Make a character, toodle around town for a while, get to understand basic commands, maybe even get into combat. Once you feel more prepared, really start getting into it. It'll come natural.
Even people who have played lots of other MUDs, even the roleplay-focused ones, still have to learn Sindome. You're not at a disadvantage compared to them.
Use the help systems. Read "@newbie" and "@rules". Examine people, places and things wit the "examine" command. Search in the Sindome website search field above for "how do you progress in the game". Welcome and have fun!
This is the place to start: http://www.sindome.org/help/
Help files, lore and the boards will be your godsend from a mechanical standpoint. Read them, learn them and remember them. If you don't? Don't get embarrassed. We were all new once; to both Sindome and any other game. There's a learning process and that's okay, it's to be expected. Don't feel shy if you have questions to ask; and don't feel shamed if you are told to ask it ICly instead. Remember, mechanics are secondary to roleplay here; you should aim to keep that as your goal. And on that note:
You are here to have fun, but fun in a roleplay intensive multiplayer game is a much broader goal than it is in an fps or even an MMO. You must consider not only yourself, but others as well; likewise, they should do the same to you. Characters may be selfish, greedy, cruel, harsh, brusque and want to win at all costs. As a player, we should be the exact opposite. We're all here to participate in a live, interactive story which has no end and provides countless opportunities for us to experience and explore mindsets and characters to our heart's content. Thus, I think the most important and basic thing I could offer to you is to remember to be kind and patient with your fellow players; make sure they're able to trust you and feel comfortable in all scenes (well, at least from a perspective of playing; certainly, uncomfortable but not abusive/out-of-line IC actions may make a player feel unnerved - but that is a good thing), and know you're here to be inclusive in your character's story.
I hope, in turn, you will find yourself greeted with the same in most of your encounters. If you do, I think you'll see even the steepest of learning curves become easier to navigate, and you'll get the hang of it in no time. Shyness, embarrassment and time are your only obstacles and two of them are able to be conquered.
Unless you've found a time machine, then, well. I'm jealous.