Despite attempts to look calm, cool, and collected like any other man, there are a number a things I will do around an initial date that clue you in that I'm interested. Here are a few:
1. Completing the Date
It may not indicate that you're the apple of my eye, but it does indicate that you're not a total disaster. Most people are courteous enough to do the absolute minimum on a date: finish whatever activity you're doing together and devote sufficient time out of respect for the other person. But some situations are such utter disaster, things must be cut short.
2. One on One
If I'm into you, and comfortable, I won't want to "share" you. A common tactic to combat a boring date is calling in "reinforcement" friends to "dilute" you. I'm naturally talkative with those around me, but if I invite everyone else around us into our party, I might be looking for a more interesting outlet.
3. Extending the Date
Suggesting something (other than going back to someone's place) after dinner like taking a walk, grabbing a drink, going for dessert, catching a movie, etc., indicates I'm asking for an encore.
4. Suggesting Another Date
Sometimes I get so excited during a first date I play my cards by suggesting other things we should do together. A common time to suggest another date is at the end of the date, though some guys just say this to be friendly.
5. Friendly Follow-Up Right After You Say Good-bye
Sometimes after a date, I'll text the girl telling her I had a great time, out of sheer giddiness. If I'm not interested after the date, I'll head straight home and begin my process of fading out of this girl's life.
Hold me to a higher standard than one extra date, or one call back after the initial date. How many times have you gone on a few dates only to have it fizzle out? You can't be sure I'm interested until we've gone out consistently for more than a month.