Tip #5: Don't Overlap or Pull Colour Through the Mids and Ends of Your Hair
In a similar vein to root touch-ups, Schaudt suggests that anyone with preexisting highlights or dyes keep their DIY colour concentrated in one area. "Don't overlap or pull any colour through the mids or ends," she said. "This will create unwanted banding or cover any highlights you wish to keep." Although these issues are both fixable in the salon, they'll add time and money to your visit.
What to Try: Christophe Robin Temporary Colour Gel ($51)