People ask me about dressing novenas sometimes - they'll have problems because their candles won't burn, or they aren't sure how much oil to use, or how much plant/herb matter, or whatever. So I thought I'd try to show y'all what i do. There's more than one way to skin a cat, but this works for me.
When I'm dressing a novena light, I use a chopstick to poke three holes in the wax around the wick. Yes, that's a big hole. No, it won't go all the way to the bottom. It's ok.
You can't really see all of them here, 'cause I've already sprinkled some herbs and oil and glitter and they are slightly obscured, but you get the idea.
After I do this, I put bits of herbs and curios into the holes. Anything chunky or that isn't quite a powder that needs to be added goes into the holes. Use something to poke herbs down into the hole if they don't want to go, or else they'll escape when you do the next bit: Then I drizzle some oil around the top, making sure it gets into the holes. I then cover the surface with oil by rubbing it with my finger, clockwise or counterclockwise as appropriate for the work.
Finally, whatever herbs are in powder, or close-to-powder, form, then get sprinkled lightly on the top of the oiled surface. I especially like to use powdered resins when I need to add resins. A powdered frankincense will keep your candle from hitting a lump of resin as it burns, which might go up by itself with a separate flame and/or blacken the glass.
A sprinkle of glitter - I recommend the really fine, expensive stuff instead of the chunky kindergarten stuff, if you can get it - finishes the dressing. Do not overdo it!
See? Just a light, fairly even dusting will do ya' right. I probably go heavier on the oil than many folks, but if you poke holes, it shouldn't be a problem. My lights hardly ever drown, and don't need a lot of poking and tending the first few days in general. Go light on the herbs to avoid unexpected conflagrations, and invest in powdered herbs if you're not the mortar and pestle (or coffee grinder) type, or if you need to use a lot of woody stuff like John the Conqueror root, which you're better off hitting with a hammer than trying to powder by hand.
Sometimes wicks are bad, or there are air pockets or problems within the candle itself - these novena candles are mass produced - I don't pour my own. But if you poke holes and avoid dropping huge chunks of woody herbs and resins into your candle, you should have nice, clean-burning dressed novena lights. (Sometime when I have a chance I'll explain how oil prices interfered with etymology, and why novena lights, which ought to burn for nine days, usually only burn for about 5 in this day and age. I'm conflating novenas and 7 day candles here, not because I'm not aware of the difference - or what differences there used to be - but because for the purposes of this post, it doesn't really matter).
What if you need to fix a candle that is not made of the soft wax novenas are usually made of, but is made of harder paraffin? The Ninja Cat shows you one way here.