Hi there :) I really have no secret. If you want a flat red, get a box blonde and then if you put a semi permanent red (I’ll post a link at the end) If you want a toned, different shade of red, I use box reds. However I hate my hair even it is the slightest bit faded, so I dye it every two weeks. Also my hair is great for dying, it bleaches really well. If you bleach get a good conditioner.
http://www.neonmegastore.com/hair-products/la-riche-directions-hair-dye/la-riche-directions-hair-dye.html I used Pillar Box Red. Sorry for rambling. Xx