A sharp needle, you can find them at any craft store.
Everything I've read suggests that you replace the needle prior to beginning EACH and EVERY new project. I haven't always performed this step, but it probably helps. I'm a complete hack with sewing....er, I mean injecting thread. That being written, my circa 1935 single stich Singer can push thread through multiple layers of webbing and cloth so I don't worry too much and just plunge away.
It probably matters more if sewing stuff for ultralight backpacking or other ventures where the cloth can snag on the slightest of burrs on your needle. As for me, I sew nylon webbing and cordura cloth. If it snags, I don't want it!
For thread I've used upholstery / outdoor thread made from poly or nylon. Neither has let me down (quit literally) so far.