Well, first of all, don't do it alone. When I went on my first shroom trip, I had a friend with me. We could talk about what we were experiencing and it made it less scary. Another thing is to have some snacks and water nearby. You might get thirsty or hungry during the trip. And don't overdo the dosage. Start with a small amount to see how your body reacts.
For a great first shroom trip experience, plan ahead. Make sure you're in a positive state of mind before you start. If you're stressed or worried, it might not go so well. I chose a place where I could be outside if I wanted to but also go inside if I felt the need for some privacy. Also, wear comfortable clothes. You don't want to be distracted by tight or itchy clothes during the trip. And trust the process. Let the shrooms take you on their journey and don't fight the feelings that come up.