Encourage her to accept the most comprehensive treatment from the outset, rather than 'take NSAIDS and come back via your GP when it's worse' - mainly because once you're off the Rheumatology books, it's an absolute bastard to convince anybody to put you back on again if you're female . Asking about starting a medication with 'and could a steroid pulse/injection to get things started before the medication starts taking effect be considered?' could mean they agree to an injection that could give her significant relief almost immediately whilst waiting for the other meds to get up to therapeutic levels.
I'd say don't accept a 'try these to help you sleep/deal with pain, it's a very low, tiny dose and they help people in pain' because 'these' are usually amitriptyline - an antidepressant prescribed off licence. I'm biased against them because they made me go a bit loopy because I wasn't depressed in the slightest, I had untreated inflammation, but as soon as they showed up on my medication history, everything physical was written off as psychological, from horrendous dizziness due to neck and shoulder inflammation following a shoulder dislocation to hands bright red and blown up like balloons.
A useful phrase could be 'No, I do not believe I am in pain and tired because I'm depressed, I'm in pain with swollen joints/early morning stiffness that persists for x hours and I would like to start medication that acts upon the inflammation, please'.
Another danger is the confrontational medical 'professional' saying 'SO, why is it that you THINK you have an inflammatory disease?'. Being able to respond with 'I think the ESR of ..., CRP of ... and a positive test for ... was a clue, but ultimately, I listened to the doctor who said these combined with my symptoms of joint swelling, early morning stiffness were consistent with a diagnosis of...'
Finally, adding on a question about other treatments, such as Podiatry/Physio referrals is handy, as they can be great for regaining function after an extended period of pain.
It's particularly hard for girls who have been socialised to be polite and agreeable, but there's a level of robustness that is sadly needed to navigate institutional sexism in medicine in order to get the most effective treatments. She needs to tap into her inner stubborness, which is what gets her out of bed in the morning whilst untreated - and answering questions politely but utterly deadpan in their resolve is so useful in ensuring she isn't sent off with a head pat and a prescription for psych meds.