Well, either you are "dating people" or you are "lying to people serially". If you do not address, up front, that you are actively going out on dates with other people, you are lying by omission.

And that's not a great place to start any relationship.

So be honest and true with everyone you meet. Look them in the eye, tell them the truth, and ask them if that is OK with them. This is Consent 101.

If the two of you are entering into the date with different understandings and intentions, that ain't gonna go well for anybody.

So. You look her in the eye, tell her that you are dating other people too, and ask if that is acceptable to her. If not, then she can move on to someone who will lie to her face, and you can move on to someone with reasonable expectations and some sense of pride and self-confidence.

If she looks you in the eye and says, "Yes. I accept that. I'm also dating other guys, too," now you get to see what kind of man you really are. Can you take that? Are you confident enough in yourself and your value as a relationship partner to invest your time in someone who is honest with you and appreciates your honesty? (Protip: There is only one correct answer to this question, because if you answer "No" then you are not ready to be out there dating, and you are doing a disservice to your dates.)

Caveats: Yes, of course there are ways to bring up conversations with other women in polite and conversationally-relevant ways. There are also ways to be a dick about it. So don't be a dick about it.

Whether or not you are female or polyamorous or whatever, there is a LOT of gold in the unfortunately titled book "The Ethical Slut". This is a great primer for how to treat other people as actual people and human beings, rather than tools for your pleasure. Consent, open conversations about "hard" subjects like contraception, etc, etc, etc. Check it out.