do well
1. To find success financially and/or in one's career. I can see from the sports car she's driving that Mary is doing well these days.
2. To benefit or fare better from, or be prudent or responsible by, doing some specific task or action. You would do well to show up to work on time tomorrow if you care to keep your job. You would do well to hire a lawyer now in case he decides to sue.
do well
1. Prosper, thrive, succeed, as in He's done well in the market. [c. 1300]
2. do well to do something. Fare better or act prudently by doing something, as in She would do well to ask permission before she leaves. [Late 1400s]