Specific healing advice for noob HFC healer(s)

Hey guys. Long time Prot/Ret Paladin player here. Recently I switched to Ret/Holy and started building my Holy set. It's not as on point as my Ret ilvl/stat wise but it's close enough. I'm a ilvl 688 Holy Paladin. I should be fine healing Normal HFC right? I assume I may get an upgrade or two along the way so maybe by the last two bosses i'll hit 690.

My main question is for all you healers(not just HPals, i'll get to you guys in a sec lol). What did you wish you knew going into HFC healing that you had to learn the hard way, or that someone like me may not know. Tips, "tricks", little things, big things. I'm stepping into Normal HFC raid healing for the first time in quite some time so anything would help.

I'm basically looking for general advice. Not stupid stuff, but both general HFC healing advice and HPal specific HFC healing advice.

I know it's a lot to ask, but i'm "trying out" for this guild(they know Ret is my best spec but they need the healer and they said if it turns out bad I can go Ret and they'll bring in someone) so i'm trying to at least impress them somewhat with my healing. Don't have to be #1 HPS but just show the RL that, hey this guy is pretty good for his first time in here, especially healing!

Thanks guys!