first off camera flash shoot indoors, NERVOUS!

okay, Im rather nervous, any tips folks?
Ive been shooting for about 2 years steady now and finally took the jump to off camera flash(shoot through/bounce umbrella and my sigma dg super.. with pc sync chord)
Im doing my first real indoor shoot this friday with a fun model friend..Sadly its in my living room, but I have 10 foot ceilings and a backdrop system with a multi colored muslin 10x20...It is..well for lack of a better word cramped...

Its a small space and Im just hoping I can expose her correctly and will give some depth to the lighting... I am planning on doing full body shots, which some might think isn't a good idea with just 1 light...(I also have 2 pretty large reflectors)
I can afford to get her about 4 feet from the backdrop...my umbrella will undoubtedly light her and the background...which is okay, because I don't have a second light to light the background and its a pretty funky color...

Does anyone have any good pointers or tips for this set up? She is going to be in sexy 80's gym attire, if that makes any sense lol
any help greatly appreciated

You said the shoot is for a fun model friend, just have fun while doing it

To make it easier on the day of the shoot, do a test session with the gears you will be using before Friday. Find out what aperture to use to get the best out of the model and the BG, the flash to subject distance and the power setting on the Sigma to give you that aperture. Think of few different lighting arrangements that will give you looks or style. She's a model, then she should know how to pose. If not sure, grab some pictures from net, or clip some pages off the magazines that are related to you theme, and just try your best to duplicate them.

On Friday, all you have to do is to press the shutter.

Of course, it's easy to say than done

Practice, practice, practice with non-breathing subjects. Shoot stuff with different shapes, colors, surfaces and study the shadow patterns you create.

The model/friend needs to know you're just learning and relatively clueless. If everyone understands that this is just for fun and practice then you won't be so nervous.

My 1-cent flash "meter" in images 5S & 6S.
Simple 2 Light Portrait Set-up

Thanks guys It is easier that she is a friend, but she is a real model..I just want to be professional around her. I have been test shooting for days...And can get pretty well exposed shots at iso 200 and 7.1...
but heres the question, shoot through?...which scatters light a bit more
or bounce umbrella?..which I know makes you lose a stop or two...
when trying to light a full body subject at its back ground

If you saw my "studio" I shot this in, you wouldn't be nervous!

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hahaa....uh change that muslin to blue and you have what Im working with

I bounce, but try both & see what you like.