Preparing emotionally for a reunion is a critical first step. The child, even if they are now an adult, needs to carefully think through the implications of a reunion and needs to plan carefully for the initial contact and the first meeting.
Once the decision has been made to reconnect, here are some pointers from those with experience about making the initial contact and the first meeting work well.
Initiate contact indirectly. Most of those who have been through a father-child reunion suggest that contact be made via email, social media, another relative or a mutual friend rather than by a direct phone call or visit. Your dad may have a new life and while he may be thrilled to reconnect, others in his life may not be as excited. So once you locate dad, make a safe initial contact through an indirect method. If he is ready to reconnect, take the opportunity. If not, let him know how to contact you and wait a while before reinitiating contact.
Don't indulge your fantasy. Most frequently, disaffected children have created a fantasy around their estranged fathers. If they were separated at a young age and the child has a fond memory of father, the fantasy might be a glowingly positive one. If the separation was bitter and angry, the fantasy may suggest that Dad's love really never died but was just pushed away. Daughters particularly, because of the daddy-daughter relationship, may have created an elaborate fantasy about Dad. As you get ready to meet again, push aside the fantasies and be be prepared for reality.
Start fresh. While every estranged relationship is complex, it is important to be prepared to start fresh when reuniting. Leave the recriminations behind; let go of the resentment. Be prepared to accept your father as a different human being. Whatever negative experiences might have occurred have probably changed him as well.
Don't bash each other or others. You may feel a need to unload a lot of your feelings on your father, and he may feel the same way. There may be a time when that would be appropriate, but the initial meeting is not that time. Make up your mind that you will not let the meeting deteriorate into a "bashing session." You should plan not to speak ill of anyone, and if starts, change the subject. Keeping the first meeting on a positive and superficial level will help you reconnect at the right pace.
Keep it short and simple. Plan to meet for a short time initially. One daughter I know invited her dad to meet her for coffee one morning. Planning on a short meeting in a public place is the best way to start. It is not threatening to either of you and can help make the initial contact positive.
Be prepared to apologize, even if things weren't your fault. An attiude of reconciliation goes a long way, and if you come prepared to accept responsibility and offer forgiveness for whatever there might be in the past, feelings will be more tender and more accepting.
Be open to a brand new relationship. Father and child reunions very seldom start off where they stopped years before. Both of you will have changed, and you both need to start connecting where you are rather than where you left off.
The first father-child reunion opportunity can be an opportunity for healing and reconnection. Going slowly, with few expectations and being prepared for a dose of new reality will help make the experience a more positive one.