When it comes to people I'm romantically interested in or not, I always seem to form in my mind thoughts that they love me back. But when said person already has a boyfriend/girlfriend, then I find it hard to imagine such things. As for people I'm not romantically interested in... I guess I can be oblivious? But, especially in the case of friends, I'll still sometimes form the same thoughts; however, I usually try to talk myself out of thinking such things because I don't want them to turn out to be true, ya know? The signs I tend to look for mostly revolves around something romantically insinuating, such as being asked to a dance or something like that. But of course I know I should keep in mind such things could also be asked in a friendly sort of manner, haha.
If I think someone likes me, well... It depends. If it's someone I'm romantically interested in, then I'll flirt with them and wait for them to confess first, I guess? On the other hand, if it's someone I'm not romantically interested in, um... I guess I'd be weary around them? Don't want anything sudden happening, after all.
As of right now all of my romantic, real life crushes (is it sad I have anime/video game crushes too) have turned into broken hearts for me. I currently have two people who I like, one female and the other male, and while we've told one another that we love each other Idk what kind of love they're talking about ^^; There's also a part of me that believes no one will ever love me romantically, but that's just my low self-esteem speaking, I guess.
And regarding how I let someone know I love them... I...honestly don't. Instead, I've cowardly told other people that I have a romantic interest in the person or people because I hope for advice, you know? It's even harder when said person already has a boyfriend/girlfriend...