Well I sell them in my shop so I know a thing or two

(plus I was slightly obsessed before we started stocking them so that helped!)
I firstly would suggest that you get a tart warmer, this is similar to an oil burner but has a deeper well for the wax to melt into, tarts are like little flat wax cakes that you put into the top instead of oil and then pop a plain tea light underneath to melt the wax. It's important that you get a proper tart burner as if you get a normail oil burner you could end up with one almighty mess if the well isn't big enough to take the wax. Also some taller burners are too tall to let the heat from the tea light reach the tart therefore not melting it sufficiently to get a good wax pool and fragrance. A tart warmer will cost yoou about £6-10 and tarts are from about 99p, but you can get them on Fragrance of the Month for about 75p.
Tarts are a good way of trying a fragrance before commiting yourself to a jar, as some scents do smell different when they are burning to when they are just in the jar.
Burning times are:-
Tart 8 hours
Sampler Votive 15 Hours
Tea Lights 4-6 hours
Small Jar 25-40 hours
Med Jar 50-90
Large Jar 90-150
I usually have a large jar as they represent the best value for money but obviously they are a large outlay.
My fave fragrances at the moment are Winter Wonderland, Tutti Frutti, Apple Cider, Welcome Christmas, Happy Christmas, Balsam & Cedar and Red Berry & Cedar. YUMMO!
Clintons are only allowed a certain set of fragrances and they will never hold the same range that independants like us will have, they have a contract with YC that they sell through seasons usually, so you may find that after christmas there are some bargains to be had. Keep an eye out, as they usually phase out towards Jan - Feb and then re introduce some spring fragrances around Mother's Day etc as they make fantastic gifts.
Let me know if you have any more questions etc, I'm happy to help, I could gab on about these things all day! (bet you couldn't tell!

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HTH
Gems