A colleague who says one thing and does something entirely different
Many times it happens that you assign some task to a subordinate or make a course of action with a colleague, all with mutual understanding, but once it’s time to compile the end results, his/her output will be totally contrary to what was agreed. That happens when you are trying to impose something on the other without listening out what he/she has to say on the matter. Let the people express themselves and just to be on the safe side, keep on taking regular feedbacks.
People having conflict with you
Conflicts focusing solely on professional matter can at times be good for the organization. But, when these conflicts turn personal, things can get rather messy, and the onus is on the manager to take action. In these circumstances, it is best to hear out both sides and propose a solution void of any prejudice and in the best interests of the company.
Until and unless you are the CEO of the company, it is impossible for you not to find people who are jealous of you or your competitors. Try to identify such people, give them company, assure them, and make them believe that all of you are working for one common goal and it is not a rat race.
People who take you for granted
Don’t be overly nice with people; otherwise you will be taken for granted. There is nothing worse than that and only way to counter this impression is to drastically change your attitude.