Sylvia, I would just use Brian's index if you have already chosen the list of ones you want to see. Find the will film box labelled the same year and court, and you shouldn't have a problem. If you have had difficulty in the past finding the right film, the staff will help.
Within the film Arch wills are usually fairly easy to find, being numbered (and the numbers are on Brian's index), although they are sometimes one or two wills away (filmed out of order, or sometimes have a slightly different number compared to the index). You probably know that the wills are arranged by parish, and always arranged in the same order going around the island?

If your will/decree is not easily found try skimming through the wills for the whole parish - which is recommended, anyway. It doesn't take long and you may find mentions of your family under unexpected names, and lead to the discovery of unknown siblings and other relatives.
See also the list of "Defuncts" at the start of the parish, which are often marked to show whether they left a will. + means there should be one following; - means a will in the other court, but check anyway because the marks are a bit erratic, and the page is often torn and stained because it is at the beginning of the parish.

Pre-1700 wills are more difficult to find, especially for a wife/widow, because she is often recorded under her maiden name, and if her marriage hasn't been found you can only recognise who she is by the surnames of her husband and/or children if given.
Additionally, you need to look at the pre-1700 wills more carefully - no point racing through looking only at the name and parish at the top of the page, because there are sometimes two to a page with a different will/decree on the bottom part.

Sue