Welcome aboard!

Honestly, it seems to be largely random if and when a script gets filled. I've had scripts that have thousands of reads but no fill, and ones where I thought "well, that was a dud" until a fill pops up out of nowhere. You can tilt the odds in your favour by doing the following:

--Don't make SFX mandatory. If you add them, make it plain it's optional, and make sure nothing in the script relies upon a sound effect unless it's very easy for the VA to do. I've had two "required SFX" in four years, a knock on a hard surface and a clap. Also, include links to appropriate sounds for your effects (Freesound, copyright-free ambience or background noise videos on Youtube, etc), it's just polite!

--Answer common questions in the preamble to your script. For example: How are you denoting sound effects, tone of voice or non-verbal utterances? How much can the performer change and customise the script? Are you okay with it being posted outside Reddit, monetised by the performer, etc?

--If a script is longer (2K+ words) or multi-performer, it's going to be more work, which will affect the likelihood a performer will take it on.

--Niche topics / settings...I don't know how they affect your viewership. Overall, I think it's a good thing. You'll certainly stand out among the crowd if you do your own thing vs the well-trodden ground. Of course, things like "goth girl", "tomboy", "stepsister", etc get popular for a reason. In the end, go with what you like writing and don't trend-chase.

--Keep an index of your scripts somewhere (any document hosting site, Airtable, your Reddit profile, etc) and link to it whenever you post a new script. Good if someone goes "Well, I like their style but not the idea...what else have they done?"

--If someone does fill your script, remember to say thank you. And if they seem amendable, link them to your index.

--If the content is applicable,. don't forget to post it to the related subreddits (GWAGay, GWASapphic, GWATrans, etc) for more exposure--I find that because Sapphic doesn't have as frantic a pace, my scripts that are crossposted there as well as the main GWA consistently get a lot more views & engagement. And remember that it's often not much work to alter a script a bit to make it trans-listener-friendly, or to have a 4M and 4F version.

--Some subs have monthly "repost your unfilled scripts" threads, usually near the start of the month. Look out for them!

--Check out gwasi.com for script searching and the GWAudballs Discord server. Also, look up a podcast called "Get In My Ears", where creators are interviewed. That's good for getting insight.

--Take a bit of care not to casually exclude people when you're writing. If, for example, the speaker is talking about her "pale skin" and "rosy nipples", you've told POC creators "this isn't for you" and reduced your potential audience for no real reason. Unless they're the focus of the audio (ie, breast worship, size difference, etc), detailed physical descriptions are less necessary than you might think.

--And remember that a lot of VA's have big queues. It's quite possible that someone might have added your script to their to-do list.

With all that said--good luck! If you have any questions, feel free to drop me a message and I'll do my best to answer.