In an appendix to his Doctrine of the Knowledge of God, John Frame compiles a good list of 62 "maxims for theologians," dos and don'ts that essentially summarize the entire book. A few that helped me today are:
6. Do not seek to do theology without a personal knowledge of God as your friend through Christ.
39. Do engage in biblical theology, but not in a cultic spirit.
40. Do not regard your theological system as superior in any way (materially or formally) to Scripture itself. Make sure your emotional attachments and attitudes are consistent with this resolution.
59. Do admit it when you don't know the answer.
--John Frame, The Doctrine of the Knowledge of God (P&R, 1987), 375-79