Would appreciate some help!!

Hi

I have shoulder length hair with a natural curl.  I have today purchased two 14" packets of hair and the colours are 27 and 33.  I am glueing them in on the wefts.  I hate it when you can see your own hair line at the back and would welcome any hints or tips on how I can sufficiently not have my own hair show through.  I always get this when I do my own.

Any tips/hints would be welcomed.

I want it to look as natural as possible and because my own hair is so thick sometimes you can see the line at the back which I detest.  I have had it done previously by hair extensionists and they are always blending my hair in with one of those blending combs and when the hair extensions come out my hair seems to be in terrible condition so this is why I now want to do it myself.

Will I have to put the wefts very closely together when glueing them in my hair.