A few women have trouble at the start especially if you have had no experience with using microscopes, I will try and give you some hints on its use.
I think the most important hint is to have your eye as close as possible to the lens therefore shutting out as much external light and utilizing more of the internal light. Then start from one side of the focusing lens and slowly turn to focus till you see something. If you wear glasses take them off, you don't need them as it is a magnifying device.
Even if you are not ovulating, if you have put enough saliva on and have waited at least 10 minutes for it to dry you will usually see some dry air bubbles and some times some striation lines from the dried saliva. But if you are not in your ovulatory phase then you won't see the fern structure.
Make sure that you clean the lens piece after each use with an alcohol swab such as a mediswab available from chemists or a slightly damp hankie will also do. Do not use any chemical solvents to clean the lens as these may effect the veiwing glass.
Also refrain from eating or drinking up to two hours before the test and first saliva in the morning will contain the highest hormone levels. If you wear glasses there is no need to use them with the scope as it is a magnifying glass.