Just make sure the house is clean and organized. They look at the neighborhood, the lot, the exterior and the interior for condition and quality of construction. How well maintained the house appears to be is a factor. And what differences there are between your house and similar ones built about the same time.
Anything special you have done to improve the value of the house you might want to leave a note for him to see or mention it to him in person. This would be something like built-in shelves, an addition, fencing you've added, permanent wall coverings like troweled colored plaster, additional energy improvements, remodeling of kitchen or bath, or the like. This will give him some ammunition to appraise yours higher than the surrounding identically built homes from the same builder.
Be friendly if you're there, but don't inquire what he will give for an appraisal. Don't try to lead him around or follow him. He won't be there long. Absolutely do not engage with him to the point of arguing.
Beyond that, you just want it to appraise high enough for your buyer to get his loan. Typically, the lender waits on the file to pass muster before ordering the appraisal. So, yes, it is looking pretty good (but there can still be problems - just less likely).