So apparently at my sister's mobile home they have seen a women that only stays next to my sister's bedroom door. I guess the other night my sister woke up in the middle of the night to see a women reading a book in a poofy dress. My sister told my mom about it and my sister thought it was a women from a long time ago.
The mobile home used to be our great grandma and grandpa's house. I'm thinking that it might be our grandma since she had passed away this year.
Now my other sister and her boyfriend (they all live together) have been hearing a man's deep voice. Her boyfriend say's he is sensitive to spirits and say's he has been seeing spirits for a long time and it runs in his family and it seems these things have been popping up since he moved in maybe 3 or 4 months ago.
I'm skeptical about all this paranormal stuff seeing as I've never experienced anything before, but I want to contact these beings.
What's the best way to contact them?

The best way is not to do it at all. Once you attempt to do this, you open up doors for demons.
Few things in the spirit world is what they appear.

Exactly... and I'd like to add to that... if these things continue to manifest and make themselves known, you need to contact a local church and have them removed.