This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
From: John DeMar (email@example.com)
The best thing you can do is to NOT use launch lugs. Use a
launch tower instead. A polished, smooth finish makes a big
difference too. If the design allows, use a boattail and make
sure all transitions are smooth (from nosecones/payload sections,
etc.). Fin shape is a minor effect if they are relatively thin,
otherwise make sure the edges are at least rounded.
Here are some numbers for comparison:
Standard finish, no transitions, with lug: Cd = 0.88 Standard finish, no lug: 0.68 Polished finish, no lug: 0.61 Standard finish, no lug, 2:1 boattail: 0.52