The most basic, is to meet in a fairly public place for the first time. Somewhere with lots of people, a place to sit and time to talk. One needs to get a feel for each other on a personal level first, no matter how much inline talk has happened before.
As sucky as it sounds, before agreeing to go meet somewhere always have had more then text interaction with the other person. At least voice chat is a must, but ideally a video connection also. Too often people get involved online with someone who is not who they presented as. Before you go off to meet someone know exactly who you are meeting and what they look like. If the person is known in the community from gatherings and such that is good enough also.
Don't enter into the interaction with any feeling of entitlement to a specific outcome. No one is obligated to do anything. and no one should do anything because they 'feel' obligated.
It goes without saying that you should inform a trusted friend of where you are going to meet someone, and who you are meeting, and arrange a safety check in contact at some point in the evening. That person is your lifeline should you become unable to contact them. They should always know exactly where you are over the evening.
It's easy to focus on the good and great things that may happen and overlook problems in the face of that possible fun. Keep perspective. Listen to your gut.
Myriads