So you want to make a new species...
Our main concern with new content is how it fits into the existing overall storyline for the site. This includes more than just where the species is right now, we also want the history of the species to make sense and fit within existing themes. With a Sci-fi setting the big problem looming over the story is the Fermi Paradox. If we run into a high tech alien society within 100 light years of earth, we'd expect to see new alien civilizations every 100ly in all directions. With so many aliens out there, it doesn't make a lot of sense that they'd all be at the same tech level unless there was something out there filtering out civilizations past a certain point.
We have answers for this in mind for the setting, but we need new stuff to fit with those existing themes.
If your new race is low-tech, then this is a lot easier of a sell. We can just say they are relatively new and just haven't had the opportunity to build up. If they are high-tech, then we need a decent reason for why they are only a certain level of technology be it their civilization is in decline, they have plateaued, or some other reason for why they could have been around with technology for thousands of years without having gotten away from their home star system.
This template will cover some bullet-point items for your species timeline that you have the option of using to help generate a general idea of where they are in the story and what they have been doing.