Am I giving good signs of interest? Is this considered flirting?

[Anonymous]

I approach him to talk, ask about his interests, compliment him a lot, laugh at all his jokes, invited him to hangout. I've done all this, and he's reciprocated. But he's also shown interest in another girl in front of me.

[Bean2k]

Body language can include flicking the hair, eye contact, brief touching, open stances, proximity, and other gestures. Flirting may be done in an under-exaggerated, shy or frivolous style. Vocal communication of interest can include, for example,

alterations in vocal tone (such as pace, volume, and intonation),
challenges (including teasing, questions, qualifying, and feigned disinterest), which may serve to increase tension, and to test intention and congruity, and
adoration which includes offers, approval and tact, knowledge and demonstration of poise, self-assurance, smart and stylish, a commanding attitude.

[FilmGuy93]

You're doing the right things, but if he's showing interest in other women; that's not a great sign.

[Asker]

I see. I have a question if you can spare time. I invited a guy friend to a sports game. During the sport, he kept looking at my figure, showing me he's checking me out. We had good conversation getting to know each other. We ate dinner with our friends after playing a sport. He and I sat across. At the beginning of the dinner he started mentioning how he's single. He kept talking to me one on one, sharing his life, asking about mine. By the end of the night, he talked to my sister who was sitting next to me and started making more eye contact with her as he talked. He's known me and my sister for awhile and even told me how he forgot her name at one point. But he asked her that night if she was okay while she was shivering cold. He didn't ask me that. When we talked outside, he fistbumped my sister and said "We would get along well" after she said she eats practically anything. He was looking at me as he said that. My friends and I all stood in a circle and he kept cracking jokes and started making eye contact with just me, not my sister. But he was standing next to her. I'm wondering if I gave him the wrong idea that I just see him as a friend, since I did some "friendzone" things like high five and fistbump him regularly. When he mentioned that someone asked if I was his girlfriend, I didn't know what to say so I looked away. I've complimented him, called him masculine, initiated conversation with him, but I haven't physically flirted with him, which is what I can tell he likes. (He's brushed his hand against me before.) I also haven't asked him out. Is it possible he's not getting the hint or is he just more into my sister?