Sexual positions that allow for deep penetration are likely to be the best for conception as they allow the sperm to be deposited as close to the cervix as possible.
The missionary position is often recommended for this reason.
After you’ve had sex you might also like to place a pillow under your hips to tilt the pelvis and help the sperm to ‘travel’.
There is no research that proves or disproves either of these suggestions. It is completely up to you whether you wish to try these ideas out.
However, you should make sure that your partner ejaculates fully into your vagina, as this does increase the likelihood of conception.