1. Be prepared to TALK to him/her beforehand to discuss what they plan vs what you want. Dish location(s), wire locations, etc.
2. Be prepared to actually be around and within earshot; you would be amazed at people that cut & run or leave someone else there and then gripe when it not up to their specs upon returning.
3. Make sure if you have A/V gear and cabinets, to have them prepared to go and you be ready to assist.
4. Make sure you get everything you ordered, down to the remotes and B-band converters, and cables even if you do not need then now.
5. Make sure you are receiving all the channels to your satisfaction when they are done; check all sats for signal levels. (I am saying at least 87 or better - those in the know of your area can correct me).
6. Are you doing OTA with this? Remember this is not their area / job, and MPEG4 setup will not diplex with OTA, so you will need a dedicated RG6 run for this; even if YOU will be installing it later.
I am sure I missed something..