Make sure your wick is trimmed to 1/4” before lighting. If the wick is too long, the wax will not pull up the wick and the wick will extinguish.
Like a traditional cotton wicks, wood wicks do require a little attention before each burn. Be sure to gently snap off the ash or top of the burned section along the top edge and then light as usual.
If when burning the candle for long period of time you notice your flame getting too low, it may be necessary to extinguish the flame and when cool tap off any excess ash or burnt wood along the top of the wick. The flame will return to its proper height.
Be careful to not let any debris from the wick (or anything else!) fall into the candle.
Allow the candle to get a full melt pool (all the way to the edges of the container) each time you burn the candle (typically 1-2 hours) this is especially important during the first time you burn it. This prevent the candle from tunneling and ensures the candle burns evenly and you get the most from your candle.

Sometimes it just needs a re-light to allow the wax to start flowing up the wick

The wick is too far above the surface of the wax. This is counter intuitive, as we think the longer wick will make a bigger flame, but it will not. The longer the wick the harder it is for the wax to flow up the wick. Make sure the wick is trimmed to the proper height and light as normal.
There is too much ash or burnt section. Gently snap off the excess as described above.
Insufficient melt pool forming at the base of the wick. Carefully make a melt pool at the base of the wick while lighting the candle.