@MrsWinslow - I had trouble noticing fertile-quality mucus as well. If your mucus is sticky, you might try taking cough syrup. It has to be plain Robitussin - no letters or anything like that. The expectorant will thin out your mucus and can help with pregnancy. Look at a book like Taking Charge of Your Fertility for more information on the Robitussin method.
Another thing that can dry up your mucus is taking antihistamines. If you're currently on them, you might want to see if you can take a different medication while you try to conceive.
To answer the question you actually asked - if there is another way to tell when you're fertile - absolutely, there is, but you might not like it! It involves getting up close and personal with your cervix. When it is firm and closed (feels like the tip of your nose), you are probably not fertile. When it feels softer and more open (like your lips) then you may be getting close. Again, Taking Charge of Your Fertility can give you more info.