This will strongly depend of how well the reader can connect to the person .If you share strong emotional or energetic bond (or both ) between you and this person ,you can still do online reading .If this person is stranger it takes a lot of skill to try to attempt this .
Few tips you can go with :
Have the person to choose the deck
Have the person to pick one exact question .
While shuffling the cards hold in your mind the image of this person .How does this person look ,smells ,her/his personal traits and the emotions (the more love the best ) you have toward them .This aid the emotional and energy connection .Other person is advised to do the same .
I usually have the person I read for to tell me when to stop shuffling .I tell them to listen to their gut feelings ,when it tells them to stop they tell me .I found this method to work better for me than if I count to my own intuition only ,however I can do it by myself .
In order to do that some skills in energy flow and manipulation are required ,also it is good idea to ground afterwards .
You need some practice if you do not have natural skills in this type of divination .Of course having knowledge on Tarot and how to interprate its imagery is must .
I hope that helps .