Biggest mistake to avoid- favoring your client or the homeowner. Ideally, the transferring organization would like a lower valuation, because they will have to sell the house (an over-valuation will result in a loss for the company). On the other hand, the transferring employee (as all homeowners do) wants a high valuation to maximize their investment. I know this seems like a given, and appraisers are expected to be unbiased in their appraisal activities, but there will sometimes be pressure from one side and/or the other, and you are stuck right in the middle.
Be prepared to back up your valuation and adjustments. You will usually be competing directly with the best and most experienced appraisers in your area. When your report is completed, it will be compared to another appraiser's report and analyzed for differences. If one of you has made a mistake or oversight, it is going to be discovered. Make sure you measure accurately too - don't count the second story of a 2 story areas. Separate finished third floor and finished basement areas from main 2 story finished area, and adjust separately. Adjust for condition, if a room needs paint or is not neutral in color, you will be expected to adjust for that.
Pay close attention to market supply. When average days on market for listings is over 4 months, you may have to make a forecasting adjustment. If property is in a rapidly appreciating or declining market, you will have to reflect this in your analysis too.
Good part about relo appraising is that Skippy is eliminated from your competition, because those who don't really know how to "appraise" won't last long as relocation appraisers. Their incompetence is their reward, as this is one segment of the appraisal industry where quality still does matter.