First things first, why arent you getting along with wella? its a good brand that some of my hds have trained using this, but obv i have converted them to different brands, by ensure they know the colour theory/taking them on courses etc.
Are you working for yourself mobile? or within a salon? If in a salon, they may choose to ease you into expanding on your existing shade chart knowledge.
I own a salon and i find there are so many brands that you can affliate yourself with, whatever price bracket, but the main point is What works for you?
Now i understand that you practically just qualified, but do you feel comfortable being thrown in the deep end without progessing further within your training?
Mix ratios are very important basis to a colour, do a refresher course if you have to, if you want to use the best maybe its suited to thinking, researching for yourself which products/ brands you know about, so that you feel confident and know the whichever theory there is behind it. (sorry if it seems harsh but im gona offer you the truth in terms of real world/clients that would turn away if you dont have a clue) hths xoxo