Ah, yes now the Kama Sutra I have tried before.
If you're asking the best positions vs. the most appropriate positions for beginners then that's two different lists.
Some of the best positions are probably not ideal for beginners, unless you love gymnastics and really pushing your body in the gym.
Even if you're buff though, some of those stretches are really hard to do.
Anyway, I'd recommend
Sammukha (Similar to banging against a wall)
Piditaka (almost like her legs over her head, but with this legs bent and her clutching her knees, with feet resting on his chest. Then he kneels and enters her from almost a side position.
Virsha (similar to reverse cowgirl, if you get the phrase)
Milk and Water Embrace (Kind of difficult but not impossible. He sits on some stairs or maybe a chair, but it's better to put his weight on his hands. She reverse straddles him but holds onto his legs for support).
Indrani (more familiar version of Piditaka, missionary position but with her legs up, ankles resting on his forearms, and she holds onto her knees while he holds and caresses her stomach)
Just some ideas, but don't get too carried away with those pretzel moves meant for experts!