Find the alternate version of yourself and figure out why you're such a creep in this universe? That should help immensely. Unless she just thinks you're creepy for being so obsessed with her, in which case you need to play it cool and give her some space.
As for previous dates, which is what I assume you're asking for:
For high schoolers, good dates happen at local convenience stores and cafes. Places where you can sneak off without telling your parents. Cheap, useful and easy to be alone. Super extra bonus points if you can get trinkets like plushies or keychains there.
Failing that, you can go the more cliché routes. Movies, malls, arcades, libraries. Anywhere you can spend some time doing an activity. However, the reason this is inferior is because you're focused on the activity instead of each other. It's too distracting. Also, she probably already did those things alone in this universe...
Least acceptable would be to go to her parents or teachers and seduce them. Not literally of course. Just get them to think putting you together would be a good idea. This sucks though because no kid wants to be at the mercy of adults, and she'll definitely direct that resentment at you. But, if you genuinely have a connection... Then you can overcome it.
If not, the one who gets gunned down in this universe will be you.
Imma just share mah idea then.
You first figure out why you are such a creep and it mentioned that you are overly obsessed. By doing that, you stop the creepy shit you did and the female will slowly notice it.
You first start to improve yourself because your body in this dimension for some reason is shit and a loser. You start to exercise and stuff, stylize your looks, basically a glow-up. And a lot of women will notice and start liking you.
Basically, you start to become cool and stuff. The subplot is action, mc in this dimension is being bullied. (Your choice if you want to add this)
Once you build this foundation, the fmc will be able to notice and secretly glance at you from this onward. She felt that you suddenly disappeared in her life and now she is curious of you. Why did he suddenly disappear? Those kind of question will appear and she notice your missing presence that she got used to... Where a simp similar to dog will please her and stuff lol. (It's either now she starts to approach you, or you approach her)
Example:
•She approach you through asking related to assignments...
But you notice this suddle change. You finally got her curiosity now it's just to make her interested of you.
From your first interaction, she'll notice that you are not a fucking simp anymore... And she can't describe this confidence you emit and stuff...
With this... You can now use the past experience you had with her in use~
•You can also deepen your relationship with her through the use of her being bullied and you are the saviour LMFAO
•She just coincidentally sees how you help people and stuff and it makes her respect you even more. (You either are helping these people because you felt guilty about what you did in the past. For that reason... A misunderstanding will happen haha)
•You try to stand your ground like... She is in a situation she is having a hard time saying no but you appear and help her reject something or some shit...
~Hope you liked it~