My hair is dyed black, and i want to put blonde highlights in myself..?

I'm wondering what the easiest, and most reliable way to go about doing this to guarantee it turns out correctly. I usually touch my roots up once a month and do a complete dye job every 2- 2 1/2 months. It has been about 3 months since i've done anything to my hair, so my roots are grown out a good 5-6 inches. Because i had planned, when i got my tax money that i was going to the salon to have a cut, dye, and highlights. But some things have came up and must be taken care of so all i can afford is the cut now. I'm still wanting to dye my hair black, but i want a couple blonde streaks here and there, so if any one has any tips on how i can achieve this look without screwing it up. much appreciated!