What I'd recommend you do, when you decide you're going to start trying to conceive, is checking in with your doctor; they'll have some thoughts about avenues to pursue and any health issues you'd need to keep in mind when trying to conceive. Sperm donations are thoroughly screened so there should be little to no risk of STD/STI transmission through that avenue, but with potential partners, you can ask people when their last comprehensive STI test was done and ask about safer sex practices and the number of partners they've had since then, but if you're talking about meeting people casually that doesn't give you an opportunity to develop a lot of trust with them to know if you're willing to accept their answers as accurate or not.
In addition, I don't know what your plan would be in terms of seeking to get pregnant through a one night stand with someone, but if someone creates a pregnancy with you, whether or not you want them to be an active parent, they would have certain parental rights and would deserve to know beforehand that you're seeking to become pregnant. I really couldn't recommend trying to do this without doing a lot of research about family law in your area beforehand and being very upfront with any potential partners, even if you intend for them to be one-time or casual partners.
This is part of why I think talking to your doctor first will be helpful; they'll probably have some resources and information they can point you to.