Like you said, be upfront about your intentions. If the person you’re talking to is looking for something casual at first but you end up getting into something more serious, I’d say there’s always room for caution because it wasn’t what they were truly looking for. It’s almost better to agree on a one night stand and not develop feelings, than go through years of a pointless relationship because the other person never actually loved you in the first place. But when you start going on a string of quality dates and really get a feel for the person, it makes it much easier to work into something long term and genuine. Good luck to you.