Remove street shoes at the door. Don't be loud. Don't whistle in the house. Be polite. that may sound harsh, but Americans can be "backwoods", compared to Russians.
Be prepared for differences. This is Russia, not America. Some things work a little differently here. BUT it has always been safe to walk the streets. School children may be out at 12.30 or 18.00. 18 oclock? No, six in the evening, but schedules ALL say 18.00, 19.30 etc. Prevents "I thought mt train was at 8 in the EVENING!!" and it left 11 and a half hours ago! So you will see children ay any hour of the day walking. It is safe.
If you are black or Hispanic or any dark-skinned person, don't think "skinheads" are waiting for you. Many African students come to Moscow to study. Mexican and other Hispanics usually look like Tatars, and there are many Tatars in Russia. So the dangers associated with being a different race is not there. Russia is really safe.
I don't know much about traveling but I do know that when you travel you should probably learn a few of the basic words in that language. You'll have someone with that speaks Russian so it'll be easier but if you're ever alone at any point its good to know something on your own. Also know what offends the culture as well. You do not want to offend his family in anyway I'm sure
Nothing is going to happen to you, millions of tourists visit Russia each year and return home safely.
Just remember that you need a passport, you must get a visa for Russia through the Russian Embassy - apply well before you need to travel, and you should take out travel insurance.
The USA is far more dangerous than most other countries!!
