One of the things I've noticed is that some people are getting a bit carried away with regard to reading the omens after a candle burn. I know one woman mentioned to me that she pulled up a chair and studied the glass for about a hour, writing down details. I think that's a bit much. The glass is not a crystal ball. Omens should be picked up rather quickly. Below are some advice I would give on this matter.
1. The candle wants to openly communicate the omens. The candle will not be subtle, coy, tricky or even passive-aggressive. The candle omens are straightforward.
2. The candle omens are quick to pick up on and do not require a lengthy time to interpret.
3. The candle gives omens the entire time of the burn and not just at the end. For example, if you notice that wax is building up heavily on the sides of a glass candle and then later on all of it melts and burns away, then this means that there will be further obstacles in the future but that the person will ultimately prevail and overcome them. If you only read the candle at the end then it would imply that it would be smooth sailing the entire way until the manifestation of the goal/desire which is not what the candle is actually communicating at all in this scenario.
5. When working with candles it's important to be able to switch back-and-forth between two different mind frames. An active mind frame is needed to push out one's desire into the universe so that it can be manifested into reality. However, to read the candle one needs to then switch to a passive or receptive state so that one can be able to perceive the omens. With practice the transitions between these two mind frames will become easier and will require little effort to achieve.
6. Not every omen is good. Not every omen is bad. For some reason I am seeing more and more of people who always interpret every candle omen as being good. So if your glass candle shatters and burns your house down, then that's really good because the candle is desperate to work for you! Likewise there are quite a few "Negative Nancies" out there who are very pessimistic and interpret everything in a negative light. Avoid an overly optimistic or pessimistic attitude. Choose a middle road between them. Be open to the good and the bad omens.
7. Not everyone is going to be unbiased enough to read the omens on their own candles. If after many, many failed tries one might wish to hire a worker to set candles for them and read the burn.
8. If all the omens happen to be negative set a second light for clarification.
9. Know your candles. Know where you burn them. If you are burning a new type of candle for the first time or are wanting to burn a candle in a new place, set a test light just to see how the candle burns. Some candles are poorly made and will often leave so-called negative omens but which aren't really negative omens because all of those same candles burn the same horrible way. Some locations are also poor choices to burn candles and may not have level surfaces or may be located next to a window or door where there are drafts.
10. Don't over think it and don't force it. If you don't see an image in left-over wax then don't try to force it or spend a lengthy time staring at it. An omen in the form of an image will jump out at you. The same with any images on the glass. There's no need to stare it down like you would a person in a blinking contest.
These are just some pointers. With time people should get the hang of it. Practice does make perfect and experience is the best teacher.