Hi Cheryl,You asked, "How can the loved ones left behind know if someone is trying to contact us from the afterlife and how can we try to contact them?"
Most important, don't try to figure out whether you're getting messages from them. Live your life in constant contact. Don't doubt. Don't try to analyze what you're getting. Don't try to decide if it's a "message" or a warm memory.
You're continually being helped and influenced by people on the next plane of life: loved ones, guides, helpers, and others. They want to help you, to let you feel loved, and in the case of loved ones, to let you know they're all right.
When you feel a warm feeling, hear a song that reminds you of them, smell a smell, remember something you loved together, all of those things are wonderful. They're part of your continued relationship with your loved one. Some are inspired at the moment by them--many more than people realize. Some you remember or feel and you're inspiring them, because they receive your loving thoughts and feelings. Just enjoy them! Don't try to analyze them.
You have a new relationship. It takes some adjustment because it's different. Don't think of communication as you had it in the old relationship. Don't listen for words or look for manifestations in bodily form. Those were part of your relationship on the physical plane. Now feel the feelings. Get the messages that are unspoken. Every memory you have comes either from them to you or is being sent from you to them. They're all part of this new relationship. Just enjoy them.
You also can enter into a little more purposeful connection. Watch Phil G's video at http://www.youtube.com/watch?v=jN4SOjwY2Mw. The most important thing is to let yourself be open to anything, without expectation, frustration, or doubt. Relax and sink into the moment.
Accept everything that comes that is connected with your loved one as a connection. Don't analyze and don't doubt.
Love and peace, Craig