I hear a lot of good things about your liquid
@PlumeBlu so any advice on colouring would be great
I have three I use colouring in just because (for me) the colour worked with the flavours better than the colours naturally, I use a very minute amount though and usually 0.02 or 0.04%.
Colourings are one thing that are totally unknown for vaping, safety wise at least so no-one is really able to say what effects they might have down the line and that is the reason that a lot of decent juice vendors who use colours will specify this on their listings. I try to use natural colours where possible and only use colour+pg with nothing else added, some of my juices are coloured naturally (such as liquorice) and that carries through to the juice so I specify this also in the listing.
Really though, if you want a flavour that is coloured you need to balance out what you class as a risk, if you smoked before then in my view any of this risk is still negligible by comparison.
Things to avoid in colourings:
oil - never add oil to a mix
stabilisers - often and indicator that the ingredients will split and can sometimes indicate that oils are present
gelling agents - made to bind and gum up ingredients which will just foul a wick
E numbers are easily searched, even natural colours will carry an e number, you can use ones made from spirulina for blue and green if you use a bit of yellow too or much less for an aqua/turquoise, beetroot or carmine for red, yellow is often turmeric and annato. Brilliant blue, tartrazine are other alternatives for blue and yellow.
Just remember that a little goes a very long way usually, 0.02% of my blue is 1 drop in about 50ml of juice.
Hope this helps