you don't have to do anything but have sex to get pregnant, there are definitely ways to increase your chances. Sperm can live up to 5 days, that is for a regular healthy male in a regular healthy female.
1i would try to see if you can be intimate more often, but make sure you're enjoying it! Typically the suggestion is 3 times the week you ovulate, where you don't know I'd see if it's possible to do that every week.
2 if you lay with your hips up or with a pillow under your hips for up to 5 minutes then it decreases the chance of the sperm to spill out.
There are many other ways to try also, talk with your doctor if you are havering trouble!
You can learn how to track your cycles and try to predict ovulation. I always tell people to read "Deanna's Plan". If you join the TTC Group it has a link to the info for it.
http://www.medhelp.org/forums/Trying-to-conceive/show/461?controller=forums&action=show&id=461&camp=msc
Once a week is difficult but if timing is right then it could happen. It would probably take a long time I would think. Sperm can live in a good environment for up to 5 days. You don't have to lay a certain way but people do say to just lay there without getting up for a little bit.