The world of candle making is never perfect. Sometimes you get great candles, smooth with strong scent throw, and sometimes... well, sometimes you just don't...
That's why troubleshooting tips are always helpful.
And that's the best way to learn: either from your own experience, or from other's.
An good example of CandleMaking.org.uk's troubleshooting tips would be how to prevent air bubbles in the wax (tap on the side of the mold after you pour, and make sure the candle doesn't cool down too quickly), or the common problem of a smoky candle (the wick might be too large).
Feel free to share your own experience and tips!
Eran.