Great question, and I’m so glad you’re already thinking about this! We need way more doctors and medical staff like you 🙂

This is going to be really long because it turned into a rambling backstory! XD

General advice:

• Just because we live with the pain and symptoms all the time doesn’t mean it’s easier for us than other people. We do learn to cope and ignore it though, so sometimes we’ll act indifferent when talking about pain and symptoms.
• Believe us by default. Even if our symptoms aren’t visible, even if we don’t look or act like we’re in pain – give us the benefit of the doubt. 
• Some people do fake pain for painkillers. However, a majority of people with chronic conditions don’t get the treatment we need because people fear we’re faking. (It took me years to get treatment and I wasn’t remotely asking for painkillers, just something to help my body recover from whatever was going on.)
• I know self-diagnosis can seem icky to people in the medical profession, but instead of shooting it down, ask them why they feel they fit for that diagnosis. Chances are they’ve given it a LOT of thought and it will probably help both of you.
• If they have a diagnosis, assume they know as much (if not more) about it than you do. Treat them like an equal when it comes to medical knowledge, but encourage them to ask for clarification if anything/any word doesn’t make sense. 
• If they’re staying in the hospital, ask them: “What is it that you normally do to help ease this pain/flare/etc.?” if they respond with something, see if you can come up with some things that they could do to mimic that and help manage symptoms. 
• If they’re a teen, sometimes it’s nicer if their parents aren’t in the room with you the whole time. Give them a chance to speak for themselves. 

My best experiences:

• Being in the hospital or ER and having nurses that genuinely want to chat and tell you about their day and treat you like a normal person. It’s so refreshing! Normally I’m treated as a lab rat or as someone who is such a poor sad victim who needs sympathy uwu. Treat me like a person!
• My current doctor (a Lyme specialist) caught on pretty quickly that I know my shit and a lot of medical jargon, so he speaks to me like he speaks to his peers and it’s so refreshing. 
• Any nurse, doctor, phlebotomist, ultra-sound tech, etc. who bothers to talk to me besides the needed dialog is so freaking nice. A lot of times you feel like your humanity is being stripped away, and even if they’re basic small talk questions or they just ramble about themselves gives you something to hold onto. I know I’ve said it before but this one is really important!
• Doctors and specialists that act like they believe you and ask you questions related to symptoms instead of “well what could YOU be doing that’s causing this” and “you MUST be hiding a mental illness, that explains everything”. 

My worst experiences (backstory)

• Picture this: A scared, young teen who legitimately thinks she may be dying. She finally convinces her mom to drive her to the ER, because something is seriously wrong. She then sits in the waiting room for two hours, is put in a room for another hour or two, and then someone finally comes in. They ask her about her pain level and maybe one or two other questions. They ask if she’s pregnant and she says no. They make her pee in a cup anyways or they won’t proceed. Shocker, she’s not pregnant. They take some blood but find nothing immediately wrong. They tell her to stay hydrated and take some ibuprofen. Maybe see a therapist because teenage girls have depression. She goes home in the same amount of pain but far more tired.
• This was my life. For years. Whenever I saw doctors, they’d only talk to my mom. They made me fill out these little checklists that were obviously for anxiety and depression. I was losing weight faster than I could gain it. They made me fill out an eating disorder checklist. I was sent to numerous specialists and they all couldn’t find anything, would ask me about how stressful my school life was (I was HOMESCHOOLED), and then refer me to a different specialist. 
• I finally found a doctor who would admit “I have no clue what’s going on.” She said “I want to run a BUNCH of blood tests. The blood draw is going to be awful, they’re going to take a lot. But we need to find some answers.” The results came back through my old doctors. They called me, freaking out because “It’s not mental health problems, you have life-threatening infections that we didn’t test for because we didn’t believe it might have been related to a tick”. I was put on 3 different antibiotics and an antiviral for TWO YEARS. 
• The whole process of finding someone who would even test me for anything besides depression or a specific thing took a year and a half. At that point, the infections were so bad I probably would’ve died within the next year. 

Treat them like a person. Believe them. Even the teenagers. If they’re willing to do anything to find a diagnosis, do anything you can to help them find it. Trust that they know their body best. BELIEVE THEM!