I have some history with this type of game, because I played its predecessor Tiny Tower. I've found that a number of different strategies could be used to move bitizens in, obviously with the ultimate goal of having every level with 3 dream jobbers, each with Skill 9.
What I will call the "Busy-Body" approach to bitizen move-in is to accept every bitizen that walks in the door. Due to the fact that dream jobbers are far more valuable than Skill 9, this approach seems appealing to get the maximum benefit in the least amount of time. The problem with this approach is that you wind up moving bitizens around a lot, and eventually you are faced with evicting a bunch of the lower skilled bitizens anyway. Although there are some benefits in quickly get dream jobbers, I found this strategy involved a lot of work in the mid and later stages of the game.
This approach could work in Tiny Tower, but in Tiny Death Star a restriction has been added such that you can't move bitizens around when you have 10 or more unemployed bitizens. This makes it very difficult to be active in moving bitizens around, unless you have very close to the number of bitizens you need to work in all your shops. The bitizen unemployment restriction makes this strategy even less appealing, in my opinion
The "Perfectionist" strategy is to only allow Skill 9 bitizens to move into your Death Star, and only if there are fewer than 3 bitizens with the dream job of the bitizen you are moving in (obviously having 4+ bitizens with the same dream job makes some of them rather useless). While this seems like a rather conservative strategy, it seems to work better than would be expected. The process of moving bitizens in takes longer, but this can be offset by buying residential floors early and often.
I first adopted this strategy when I lost my game data for Tiny Tower and had to restart. I just finished moving in my last bitizen, such that every job is covered with a dream jobber and every dream jobber has Skill 9. I found that the Perfectionist strategy worked so well in Tiny Tower, that I adopted it outright when I started playing Tiny Death Star.
Have a different move-in strategy? I'd be glad to hear it.