Start with a few good designs:
1,2,3,4,5
Make a new permutation for 2. You don't know which one you like best.
1,2a,2b,3,4,5
Update the design for 1. Also, you don't like 5, throw it out.
1.1,2a,2b,3,4
Use the best attributes of 3 and 4 to make a new design. Also make a new alien.
1.1,2a,2b,3/4,6
You could combine the attributes of both 2s to make a new alien, but the original permutations still look good. What do you do?
1.1,2a,2b,2ab,3/4,6
3 and 4 would work on their own if they were updated, but the combination is still cool
1.1,2a,2b,2ab,3.1,4.1,3/4,6
Make a new alien. It's also a throwback to the old number 5 in some ways.
1.1