Your first introduction to this stranger is typically a photograph and depending on the dating site, a few details about your potential date.
The only issue is a big one. Not everyone is authentic with their intentions.
I have known friends who have had great success via internet dating. Some are now married with children, others are in committed relationships and there are a few who continue to desperately seek a life partner and make it obvious from the get go. Unless you portray that in your profile beware of the serial daters.
To me, it's brilliant when someone states what they want from the beginning. It puts us on a level playing field where we can immediately (confidently) move forward, knowing what each person is looking for.
Unfortunately, there are a few people out there that portray one image online but deliver something else in person.
Some of the concerning signs are the dialogues and words that are used. Nothing is more disarming than a person calling you "honey, sweetie or babe" within 24 hours of meeting you online. You haven't met them in person and if you have, you don't know them well enough to use those terms of endearments. If someone is that familiar with you from the get-go they are familiar with everyone else that they meet online too.
Besides that, don't you want a level of mutual respect and trust to build so that you feel implicitly close to that person and so that intimacy is very comfortable for you?
I recommend you check the dialogue from the beginning. Familiarity too early on can be a warning sign - be aware and take care.