thanks for the thread I've been obsessed with the show too about concubine Lin, I could sum up her strength in two big points:
1 her ability to come up with ideas, solution, plans and save herself when she is in very bad situations/hits rock bottom.
ex: - she was able to become a successful concubine, and make many comebacks even after her family gets destroyed/loses everything - when her husband got imprisoned in the castle she didn't lose time and went to make money to save herself.
this point becomes clearer if we compare her with the main wife who get's triggered easily, and loses herself/goes into a rage episode or a meltdown at every small inconvenience, she couldn't control herself / think of solutions, she mostly just cried and whined.
2 the second point is the fact that she was shameless and morally bankrupt, she was ready to do anything and go to any length to achieve her big plan) ex: killing ming lan's mom,making her daughter seduce /sleep with the count's son
I wasn't really a big fan of hers and didn't find her admirable, I thought she was a pretty average manipulator ,overconfident and arrogant for the level of her skills. her plans worked mainly because her husband "loved" her / she knew how to play him (using his mom's story).
her blind trust in her husband's love and loyalty (she thought he would never give her up), her arrogance and her devotion to make her big plan (marrying molan to the count's son) a success no matter what, is what caused her downfall.