Besides the tips you mention I also straighten the wick if necessary . The most important tip is to trim the wick , but , not too short . I've done that many times & it causes the wick to drown & sometimes tunnel .
U always wanna burn the candel for a 3 to 4 hours on the first light and if u experience tunneling u can qrap the candel with aluminkkn foil and burn the candel and it will even out