Best hair color or tips for stubborn grey roots?

Hi. I have to color my roots because of my stubborn grey every 3 weeks. And that's stretching it. What is the best brand of hair color to use that lasts a long time, and do you have good tips to make the color last longer. I color my own because I cant afford to get it professionally done. I use Clairol for 'stubborn grays'. Thank you in advance :)Best hair color or tips for stubborn grey roots?
I have resistant grey and I like Feria colors. All of their dye I've used faded less than any other. Different hair will respond to different products obviously. What volume developer do you use? I use 40, but my natural color is nearly black like a level 3 and I use a reddish brown dye that lightens it to probably a level 6.Best hair color or tips for stubborn grey roots?
The lighter shade of color you use won't show the grey so soon. The darker of shade you go ,the grey will show quicker. Brunettes always show grey sooner than people with blonde or lighter hair.