A good way to differentiate between a guy who is genuinely interested and wants something serious as opposed to a guy who just wants to hook up is in how intent they are to get to know you.
A player will often start flirting with you very quickly upon meeting or approaching you.
A serious guy on the other hand will ask you more substantive questions about yourself and build some rapport with you first before even thinking about flirting with you.
A good way to tell immediately, based on how they act, is by how patient they are in the conversation.
If the guy is already bragging or trying to get you to come over to his place or meet up with him, there’s a good chance he’s a player.
However, if the guy takes his time and asks you questions while really paying attention to the answers that you give him and following up on them with further questions, he is most likely a serious guy who is genuinely interested in you.
When a player flirts with you, he will typically make sexual references.
However, when a serious guy flirts with you, he will normally play it safe at first.
He may compliment you on something more unique to your personality than on something superficial.
In other words, he may compliment you on something that he has learned about you through the process of having conversations with you as opposed to just merely complimenting your physicality.