Nothing beats good old fashion melanin. Ah I love the Italian genes showing my olive oil skin and ability to darken without burning. Sorry to rub it in.
My best friend's sister tried that shit and it turned her orange. Looked like she spent some time hanging out at Chernobyl.
My uncle spent most of his life working out doors from early on in childhood [roughly 6 or 7] doing whatever for cash. He's a pale Irish man but tans like an Italian.
You have to be really careful with oxsoralen. You can fry yourself if you get too much exposure from tanning bed or sun. I ended up in the emergency room and was messed up skin wise for months after taking it.