One problem that I have is that on first (and even on second) dates I am way too serious and non-sexual.
The conversations flow really well (jobs, family, friends, hobbies, you name it).
The girls open up and we can talk for hours.
I also throw in some jokes.
HOWEVER: at the end of the date, it has been such a serious conversation!
More often than not, escalation seems out of place, especially if that has been the first date...
How can I make these dates more fun?
Actually: how can I bring more fun / lightheartedness to any interaction?
I am quite a serious person, until I get comfortable around someone.
I feel you. I am a pretty serious person myself. I like deep conversations. However, you are obviously not fully enjoying yourself and bringing the date to its potential. I can tell you that:
1) Sexualize the conversation. You can turn any conversation in a sexual direction. This takes practice but it is important that you don't make sex taboo and you both can talk about it lightly and have fun with it in the process. At the end of the day, the girl is there to have fun as well, and we all enjoy sex. I don't care if you are a nun, sex and physical connection are fun. So don't think she will feel repelled, just don't be a creep or overly visual/physical.
This will allow her to see you thru the lens of a potential sexual mate. If you don't and every conversation is intellectual, she will see you as a friend. You need to be able to sexualize the conversation at some point. This brings me to my next point...
2) Break the physical barrier. It is important that at some point throughout the date that you break the physical barrier. This doesn't mean throw yourself at her. Quite the opposite. Subtleness and playfulness are your friends. Now, do not do this right away. Let her warm up to you and be confident about it. Maybe when ordering a drink, turn o her and touch her shoulder and ask her what she wants. Or when opening a door you hold her lower back to introduce her to the room (although the proper way is that you enter first and hold the door from the inside, or so I've been told but either way you can still walk her through the door by holding your hand across her lower back). Or when sitting down, lightly touch her tight and break contact fast (do not hold your hand there).
What this all does is get her to feel close to you physically and break down any mental/physical barriers of touch.
3) Tease her imagination and fantasies. Unlike men, women are not visual. They get turned on by mental stimulation and emotions. Whatever she feels at a given moment is her reality, it is your job to guide those moments for her. Ask her sexual questions, and in the process find out what she likes and doesn't. Once you read into that, you can navigate and again, guide her imagination and emotions.
4) Do NOT wait until the end of the date. That is a big mistake most men make. By the end of the day you should already be making out, or there is consent and you both want it, fooling around and beyond.
5) Have fun. Truly enjoy yourself.
Hope this helps.
Modern Man Advice