While arranging details in the hobby are often different, I think confirming a fee, donation or tribute, is within the normal topics to determine while setting up a session. I don't think the "if you have to ask you can't afford it" term applies here, maybe for the over the top highest level of providers but in general it's common place to confirm. If they have reviews, there may be a fee listed with it, you can ask if that's still their fee, whether via text or speaking with them. If there is no fee with reviews or no reviews to reference you can still ask what is their going rate or fee for a half hour or hour.
1 - With most providers you'll get 4 to 7 questions before they're ready to 86 you (not see you or waste your time in return) this is where thinking with the big head is crucial. You used to get more especially if through a manager or agency but now more providers are independent, most Trans providers have always been independent.
2 - Perhaps write down several questions in advance, not 2 part questions or complex questions, questions that have a simple yes or no type answer. Focus on the 4-7 questions you need understood to go ahead with it.
3 - Don't waste one of the initial 4-7 questions on location or address, that's handled after the terms are reviewed and confirmed. After they realize you're serious and not wasting their time. They will often give you a general location and ask you to call/text them when you get there, they will then send the specific address and or room number.
4 - Remember many providers have to deal with calls from people who aren't serious, labeled time wasters, or those who are overly serious and ask too many questions, guys who think they're setting up a business meeting, you're not doing that.
5 - Some providers don't offer a 1/2 hour or quickie rate and may be offended by it. Does their add appear that they're some kind of premier of high end provider or not? Start by asking what their common rate is, if they give you a price, confirm subtly and that's an hour session?
6 - After the common rate per session is confirmed, it can be a slippery slope asking too many more defining questions of what they offer; BBBJ, DFK, rimming, both ways and so on. That is where reviews are helpful in more than just rating their looks and performance and also a list of things/questions you feel you need answered before you're comfortable enough to pull the trigger.
7 - General rules/guidelines/cautions; don't give a deposit, my only exception is if I read multiple reviews where they did so and had zero problems. Many many not even give a deposit with the exception I listed. If it looks to good to be true it often is. The use of photo shop, deep fake, posting others pictures has gradually been on the rise for decades, don't believe all the hype. Reviews are not foul proof, but often the best way to qualify a provider in the first place. Many clients will not see an previewed provider for good reason. A smaller amount of clients have learned how to navigate un-reviewed providers and had a decent level of success with it. It usually takes time to develop that ability. That ability often starts with learning how to do basic research; google their phone number, an email, a website. Google search or reverse check their photos, try to find any social media or a OnlyFans type page. The loss $10-$20 on an OF subscription for a month can often save the lost of several hundred.
Good luck and please review the girls you find, good or bad...