If you've just started TRT, personally, I say let the new T levels do the work before you consider doing a blast.
My favorite OTC supp that I've been hitting hard here lately is Beta Alanine. I tend to dose it pretty high (2g or more some days)... I'll itch like a meth head, but what it does for your training capacity (as someone who's been training) is just nucking futs.
As far as more exotic stuff, a lot of that is going to depend on your goal... I will say at 50 years old, I'd be looking into either GH or some of the GH releasing peptides. I'm only 31 but it does wonders for my skin and nails... the synergy you get with good AAS is fantastic for lean bulks or fat loss.
But yeah - start with the goal *THEN* find the prescription.