Advise for lens set up and basic lighting for portrait photography

[jamescooper]

Today i'm taking my teenage son to an old ruined castle to urge some portrait and modeling shots. Its just a multitude about but id wish to do an honest job. At my disposal I even have my Nikon D7200, A 35mm F1.8 prime, a 50mm F1.8 prime (old manual version) and a Sigma 50-150 F2.8. 
I have an on camera flash only, but do have a workmans light which will fill the space with directional light. I can tame this with a bit of white book over the sunshine if needed. it's 3 brightness settings anyway.

Can any body advise me which lens set up and lighting will give the best results?

[Wally The Confused]

The fastest way to sort that out, would be to go to  Youtube, and search the clips !

Its a bit late, to ask for advice, today !  Then expect a perfect solucion !