Generally nobody knows why you are going to a house, so just walk up relaxed and behave as you would visiting friends at their house.
The things that make you stand out are rushing to a property, hanging around near the door for a long period of time, acting oddly (wearing dark glases, Homburg hat, coat collar pulled up, balaclava wearing in the height of summer, wearing your scarf wrapped round your head), walking by the venue several times in a short period of time, talking to the SP on the phone while you're heading to the venue. That's why it does help SSs if the SP gives you most of the directions in advance, so you can find somewhere discreet away from the venue to wait and also give you enough time to get to the front on time for the start of the booking. Giving you the final directions on the start time for the booking is likely to make the SS rush to the venue, which might draw the attention of neighbours, passing police helicopters, the odd nearby geo-stationary spy satellite especially if it has happens several times a day and always with sheepish looking male visitors.
The SP and SS both want to be discreet, so try not to draw attention to yourself.