𝖶𝗋𝗂𝗍𝗂𝗇𝗀 𝖳𝗂𝗉𝗌 𝖿𝗈𝗋 𝖫𝗈𝗌𝖾𝗋𝗌

𝐖𝐫𝐢𝐭𝐢𝐧𝐠 𝐚𝐧 𝐄𝐧𝐞𝐦𝐢𝐞𝐬 𝐭𝐨 𝐋𝐨𝐯𝐞𝐫𝐬 𝐑𝐨𝐦𝐚𝐧𝐜𝐞

𝐓𝐡𝐞𝐲 𝐧𝐞𝐞𝐝 𝐚 𝐠𝐨𝐨𝐝 𝐫𝐞𝐚𝐬𝐨𝐧 𝐭𝐨 𝐡𝐚𝐭𝐞 𝐞𝐚𝐜𝐡 𝐨𝐭𝐡𝐞𝐫
Your characters need to have a believable reason to hate each other because otherwise it just becomes a "they only hate each other because the plot requires it," and readers can pick up on that really easily.
There are a lot of reasons to hate someone, but it's really important to make sure that it's something that can be overcome without it becoming abusive.
For example, having a bad first impression of someone is hatred that can be overcome. Physical, emotional, and sexual abuse is not something that can be overcome in a romantic relationship. People with conflicting ideologies can learn to coexist with each other, but not when one is a white supremacist that is discriminatory towards their partner of color.
Identifying the exact reason why they hate each other is also crucial in figuring what needs to change for them to stop hating each other - most of the times this is done in character development, as they mature enough to be able to get along.

𝐇𝐚𝐯𝐞 𝐭𝐡𝐞𝐦 𝐛𝐞 𝐜𝐨𝐦𝐩𝐚𝐭𝐢𝐛𝐥𝐞 𝐬𝐨𝐦𝐞𝐡𝐨𝐰

On some level, your characters will have to enjoy each other's company - even if it takes a long time, and even if they don't realize it at first. They can't be at each other's throats all the time, and there has to be love underneath all of that bickering.
Maybe they have similar interests that they can bond over, or similar personality traits that they can understand each other with, even as it can be a cause for friction. Or on the other hand, it might be opposites attract where they at first don't understand the other since they're so different, but come to fit together like a puzzle piece. Maybe they don't have any particular similarities or differences of note, but they have a similar goal and learn how to coexist as they work together. It doesn't matter how, and I don't believe that there's a type of couple that has to be used. So all I can say is make them compatible! Their romantic relationship ultimately needs to make sense, and not "why are these two together, they're terrible for each other!"
Finding common ground is so important!!
They need to make it there naturally on their own, not because you, the writer are nudging them in that direction.
If you can nail that compatibility, people will ship it because they see the potential, even if it's at the beginning of their story.

𝐆𝐢𝐯𝐞 𝐭𝐡𝐞𝐦 𝐚 𝐬𝐢𝐭𝐮𝐚𝐭𝐢𝐨𝐧 𝐭𝐨 𝐛𝐨𝐧𝐝
They hate each other! In order for any romance to believably happen, they need to get to know each other and connect more so that their opinions can change.
Maybe this means fighting against a common enemy so that they begrudgingly have to work together. Maybe one person has something the other person needs, and they have to spend time together to negotiate terms. Whatever the reason, they need to spend time together willingly or not, because otherwise they'll never get to know each other.

𝐓𝐚𝐤𝐞 𝐲𝐨𝐮𝐫 𝐭𝐢𝐦𝐞
Enemies to lovers relationships are often slow burns for very good reason. It takes time for people to get over hating someone, much less falling in love with them in a short span of time.
When it comes to tropes and relationships like this, there needs to be a lot of growth and care put into it. And with enemies to lovers, it's extremely important to showcase their thoughts, their attitudes, their moments. Savor them, let the reader know exactly what they think about the other person, and put love and care into the moments that they share, no matter what stage of their relationship they're in.
It's a good idea to keep track of your character development as this happens as well. It's tied extremely closely with enemies to lovers relationship development, and this will change worldviews, perceptions, and understanding of each other.
Don't rush it, take it slow. Their relationship and their perception of each other will take several babysteps to change. Let it simmer, let it stew, let them sit in it for a long time

𝐓𝐚𝐤𝐞 𝐚𝐝𝐯𝐚𝐧𝐭𝐚𝐠𝐞 𝐨𝐟 𝐭𝐡𝐞𝐢𝐫 𝐜𝐡𝐞𝐦𝐢𝐬𝐭𝐫𝐲
Most enemies to lovers relationships have a ton of chemistry between the characters, and it's one of the best things about the trope! Things like having fun when they're arguing even as they deny it, or some sexual tension that might be lurking underneath everything they do, or just riling each other up in general at the mere mention of their names or catching themselves thinking about the other... The chemistry that your characters have will vary depending on who they are, but whatever chemistry they have, put it in full force. Make it blatant, make it undeniable to everyone but the characters themselves.
The "I don't want to like them but I can't help being drawn to them" is a powerful tool to use in writing relationships like this!

𝐓𝐡𝐞 𝐢𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐜𝐞 𝐨𝐟 𝐏𝐑𝐈𝐃𝐄
In my opinion, the most important thing that needs to change for enemies to develop into a romantic relationship is PRIDE.
These characters have insane chemistry, they're constantly thinking of each other, and maybe they're even beginning to realize they're attracted to each other... So what's stopping them from immediately kissing and dating?
A lot of the times, the answer is pride. They've spent so much time and effort hating this person, fighting with them, telling others how much they hate them, etc., and all of a sudden they realize that they're in love with the other. You can't just confess to them. All of their friends will have smug smiles that say "I told you so," and god forbid that it's unrequited love on their part. What happens if they tell their enemy-turned-crush that they have feelings, and they get laughed at? That's humiliating! The fact that they even have feelings for the other person is ridiculous, it just can't happen.
A lot of the reasons why enemies to lovers can't get together immediately is due to pride. (Of course there can be a lot of other reasons too!).
So a large part of their journey will be learning how to get over their pride and toss it aside for each other because their love for each other is much greater than something as flimsy as their ego.
This internal battle is one of the things that makes it so juicy, and so satisfying to read.

𝐇𝐚𝐩𝐩𝐢𝐥𝐲 𝐄𝐯𝐞𝐫 𝐀𝐟𝐭𝐞𝐫𝐬 𝐝𝐨𝐧'𝐭 𝐚𝐥𝐰𝐚𝐲𝐬 𝐡𝐚𝐩𝐩𝐞𝐧 𝐢𝐦𝐦𝐞𝐝𝐢𝐚𝐭𝐞𝐥𝐲
Your characters went from enemies to begrudging friends, and they're finally, finally together, and all you want is to write fluff and and happily ever afters--
Not so fast!
Chances are, the beginning of a romance would be really rough for them. Yes they've developed, yes they accept each other and love each other, and yes that was a wild journey... But being friends with someone or coexisting with them is completely different from dating someone. It's likely that people will go through a bumpy period where they try to lay the foundation for their budding relationship and figure out what it'll be like, and what they both want and don't want.
Considering that they used to be enemies, it might be a colorful relationship full of fire. Things aren't magically perfect because they got together, there is still a lot to discuss and work through. They won't always get along, they won't always be lovey-dovey, they'll be annoyed by things their partner does, and that's okay. These growing pains are an important part of any relationship, and it can be really effective to showcase this in a pairing like this.

𝐜𝐫; 𝐩𝐞𝐧𝐬-𝐬𝐰𝐨𝐫𝐝𝐬-𝐬𝐭𝐮𝐟𝐟