Can I start this one with a disclaimer? Relaxing is a chemical process that can cause irreparable damage to your hair and scalp. It is very important that you do extensive research before attempting to relax your own hair. That's what I did before I attempted my first self-relaxer and I was still scared out of my mind. Below you'll find my tips for successfully self-relaxing.
Practice. The hardest part about self-relaxing is figuring out how you are going to get your entire head done (that back section especially where you can't see) within the allotted time. Once you start you are on the clock and you've got to move quickly. My tip: Practice with your deep conditioner. Apply it to your new growth and time yourself as if it's relaxer day. See how you do. Not only will you get practice, but you'll have touchable soft new growth when your finished.
Detangle First. Before you start applying the relaxer, make sure that your new growth is properly detangled. There's nothing more frustrating than having to deal with a tangle or knot while you are trying to apply the relaxer under time constraints. You might even find it helpful to pre-part the hair in each section and keep it separated with clips (not metal ones). If you have enough clips, it makes applying the relaxer a breeze.
Protect Your Scalp and Hair. If you think or know that your scalp is sensitive, I would highly recommend that you grease your scalp. It creates a protective barrier between your scalp and the relaxer. In the video below, I show you how to do it without getting it on your new growth. In addition to protecting your scalp, you should protect your previously relaxed hair by applying a grease, oil or conditioner to it. You don't have to go all the way up to where the new growth begins, but adding this extra layer of protection will come in handy if you accidentally drop some relaxer on the length of your hair. You only really want the relaxer to be on your new growth, but just think about how many times the length of your hair has been exposed to relaxer run-off. Adding that protective layer to your hair is optional but it does help to prevent breakage due to over-processing.
Timing is Everything. Part your hair into four quadrants (two in front and two in back). Aim to apply the relaxer to each quadrant within two to three minutes. The quicker you can get your relaxer applied, the more consistency you will notice with your hair's over all texture/straightness. This should leave you with ample time to go back through your hair and smooth the new growth.
Don't be Stingy. As you apply the relaxer, saturate your new growth with the relaxer. If you're using the smaller no-lye tub of relaxer. You should finish the entire tub when applying the relaxer, especially if you stretch 12 weeks plus. The more saturated your new growth is, the better/faster your hair will process.
Crown First. For most of us the crown is the most resistant part of our hair. Therefore, as you attack each quadrant make sure that you start at the crown and work your way to the perimeter of your hair.
Edges and Nape Last. Conversely, for most of us our nape and edges are most fragile or very receptive to chemical straightening. Therefore, these sections don't need as much time to get straight. Apply relaxer to these parts of your hair last. I always wait until I've completed all four sections before I apply relaxer to my edges and nape. (I actually coat the new growth at my nape in grease to make it more resistant to straightening).
Smooth it Out. Some people find this step to be optional because it doesn't actually help to make the hair straighter, but I find that it serves as a spot check for me. With my remaining relaxer application time, I go back through the sections smoothing my new growth with my fingers (I'm wearing gloves, of course). This allows me to make sure that I haven't missed any sections of hair. And if I see anywhere that looks a little sparse, I add a little extra relaxer. Also, I can see and feel how straight my new growth is getting at this point as well.
First Applied, First Rinsed. When rinsing the relaxer out, rinse the quadrants in the same order that you applied the relaxer. If you started applying relaxer to the back left quadrant. Then start rinsing that section out first and then proceed to the next one until you get to the last section that you applied relaxer to. This will help to "even out" the time difference by closing the time gap between sections.
Be Gentle. Keep your hair in the hanging down position as much as possible after rinsing. When I rinse the relaxer out, I keep my hair hanging down. I lift sections to make sure that all the relaxer is out, but I don't ruffle it up too much. Even when applying the mid step protein treatment and neutralizing it, I work with my hair while allowing it to hang down. Your hair is very fragile and you don't want to be too rough with it right now.
Neutralizing is Everything. I can not stress the importance of neutralizing your hair enough. It is crucial that the chemical processing is stopped and that your hair returns to its normal pH. I like to use a neutralizing shampoo with color alarms so that there's no guess work involved when it comes knowing whether or not my hair is properly neutralized. However, if you are not using a shampoo with color alarms, then I would suggest that you lather your hair and allow the neutralizing shampoo to sit on your hair for a few minutes (just as you would do with a conditioner). Rinse and Repeat.