Avoid taking too many potentially dangerous herbs or other medications. Even if they do help you get pregnant, many herbs have not been tested on pregnant women, so they could potentially hurt the baby.
For increasing fertility, make sure that you're both exercising a fair amount--not too much, not too little--and eating well. Stick to organic fruits and veggies to avoid the pesticides, don't eat too much junk food with synthetic flavors, don't eat cheap meat or dairy as they could contain hormones, and be sure that you're getting enough sleep and aren't stressed. These things will likely help you more than taking medications, and they will also mean that you'll have a really healthy pregnancy and a healthy baby. Best of luck!