I put vaseline on the previous texlaxed hair. I also heard of some others using conditioner. As for the application process....I mix evoo oil with the relaxer to 'water' it down some and use a pointed tip bottle so I'm only applying it to the new growth.
The texlaxed texture is different than my new growth texture so I can tell, but I also apply oil and vaseline to the previously relaxed hair... even before I go get it prefessionally done.
As everyone has said...VASELINE! I have tried other things in the past, but vaseline is the bomb. Remember to put in on thick. Don't worry too much about build-up. You are going to wash your hair 3 or 4 times anyway to neutralize!