Grapefruit juice is supposed to help with your cm. You should drink at least 1 glass a day, I think, but I always drink 2. Also, some ladies say you should drink some an hour before BD-ing - I haven't tried this (yet)
The ingredient you need to look for in the cough syrup is guaifenesin, 100mg. You also need to make sure that it is the ONLY
active ingredient as any other active ingredients can dry up cm.
opks - many swear by the clearblue and first response ones, but they are expensive especially if you don't reliably ovulate at the same time each month. Most of the ladies here use ebay cheapies. I think the general consensus is that the ones you get from fertilityplan tend to be more reliable than the babymad ones, and fertilityplan also have a few different sensitivities which can be useful as well.
Temps - take your temperature at the same time every morning (or within a half hour either way), before doing ANYTHING, immediately upon waking. You should be having proper sleep for at least 3 hours beforehand as well. I highly recommend joining fertilityfriend as there is a lot of information on there that will help you with your charting. You can join for free, and they usually give you 5 days of free VIP membership upon joining as well. You will also need to check your cm every day to reliably chart, and you'll be able to record that on your FF chart as well. Come see us in Chartstalkers thread and have a browse of our charts if you want.
Other things:
With your cm, just remember that there's a difference between quantity and quality. The cough syrup will help with quality, and the grapefruit will help with quantity. Other things that can help are drinking enough water (at least 2litres a day) and cutting back on caffeinated drinks (fizzy drink, coffee, tea, red bull, etc etc). Flaxseed oil can also help, but some find (I did) that it has a laxative effect.
For both you and your partner, a good multivit with at least 400mgs of folic acid is essential if you're not taking one already, put together with a proper diet - 3 proper meals a day. Eat lots of green veg and try to cut down on your sugar and white flour intake if you can as well.
Last but not least, the thing that NONE of us do successfully - try not to obsess.
It's true that your mind can trick your body into thinking you're preggers if you're too hung up on it, so try to keep busy if you're not already, and don't forget to enjoy each others' company!
Hope that all helps!