1) Always be honest with potential clients and do not over-promise or under-estimate costs. The lowest costs and most recent dates will ALWAYS be the one the client remembers;
2) Follow up on what you have promised and do so within the time frame you set before the client. If you cannot meet this time line, be prompt informing the client as to why and when they will expect whatever it is you promised'
3) Keep your responsibilities clear. Often clients will lean on you to assume an expanded role and this may result in you being blamed for things not truly in under your control (i.e., zoning, weather, costs, etc.). Always be clear what you have been paid to perform and keep away from "favors" or "add on's" that are not spelled out contractually. The client will nearly always remember all the things you promised and not what they paid you for.