My suggestions to anyone who might be new or struggling with establishing a character's roleplay. Have a goal for what you want from your character. Even if its just a broad idea. Engage in RP, even spontaneous interactions.
When I first started playing my character, it -was- slow, like anything I guess. I had to make some 'foundations' to get things started. Stay true to your character's goal. Meaning, don't RP something for the sake of creating RP if it isn't something you're going to follow through with or if the consequences and/or end result are going to create unwanted RP. There are no do-overs in SD.
It was hard at first to find roleplay - maybe because of where my character was, IDK. I had a lot of small, quick interactions with other players. A conversation on the mag-lev between stations. Brief introductions on an elevator. Small talk while getting tea or food. Commiserating over a beer at a pub. There were a few players that I formed a 'friendship' with but not many and certainly not enough to prevent those 'quiet' moments during gameplay that can get boring.
Don't worry if you get frustrated. I did. But, don't let that frustration make you stop. I would tell myself - it's just like RL. I'm new to a town and I'm feeling alone and invisible...what can I do to change that? What would 'I' do if I were my character - how would she react? And, I'd use those things to push me forward.
Now, things move quicker. I'm finding RP and even making some of my own. My goals are progressing and through that, there is more RP generated. Those little conversations when I was an immigrant are now turning into bigger conversations and more heavy 'non-fluffy' roleplay because I planted a 'seed'.
I think that is the important thing - at least in my opinion. It's not going to start out quick. Not usually. And, it's not going to find you unless you put in the effort. (Not saying you aren't, by any means-just making a generalization.)
As for what is the 'ideal' SD player? I don't know if there is one. I think each person has their own style. And, I think that style is borne over time and with experience.
My current character is my second one in SD. I've had lots of experience playing text-based games but this is my first one like this. My first character...she had a great deal of RP but it was probably what you would call 'fluff'. I didn't define what she was, even to myself, so in a sense, she floundered around and didn't have much depth. I had lots of people that I roleplayed with, but most of it...I would have to say she was a bit part in their world rather than being the center of her own, if that makes sense? She didn't create her own roleplay (meaning, I didn't create any roleplay specific for her) and, in the end I was dissatisfied with her because I didn't take the time to formulate her goals, be constructive with what I wanted her to do and enter into roleplay that propelled her forward in the world of SD.
Anyways, it's a learning process, I think. With the more you play, the more you develop as a character/player and the easier it gets to create and find engaging situations.