Firstly please nothing rude. This is a genuine question. I was wondering how do you know if someone has crossed over or is earthbound, without using an Ouija board (as they freak me out) I'm honestly curious. Thanks for the help to anyone who offers it. If you want any additional information please feel free to pm me or ask in the comments. Blessed be!
meditation, when you relax they can contact you in this state. they have been known to enter your dreams though if this was recent i wouldn't trust it. skrying, ask/think questions and images should appear to answer them. automatic writng where you go into a trance like state allowing the spirit to take over and write something for you. pendulum, where you get a crystal attached to a string and let the spirit move it for 'yes', 'no', 'don't know', or 'don't want to answer'.
i believe divination tools such as runes and tarot have been used, but i have never used them for this reason so i can't say for certain. you would have better luck if you have a photo, some of their belongings and/or perfume/cologne/favourite scent on hand to specify who you wish to speak with. there are other methods, those are more common ways.