Grapefruit juice apparently is very good.

With DD I had been going to a Naturopath & she gave me some tablets to take to increase CM, can't remember the name but they were only available from a Naturopath (or similar). After a couple of months I noticed an increase & added in the grapefruit juice (1 glass every morning) just in case it would help (we had been TTC for 2 yrs), I fell pregnant after a couple of cycles of the combined tablets & juice.

With this pregnancy I had been drinking the GF juice just the one month, which is the cycle I fell pregnant & we only BD twice (but I remember noticing heaps of CM)