It's not usually necessary- if the first coat of emulsion is patchy or insufficient, then just apply one or two coats more.
you should put 'an' before electric because the first letter of the next word is a vowel
An or the
No.
No.
you should do it about 15-30 seconds before you turn
Yes, you should put a comma before "as" when it is used as a conjunction in a sentence.
put your goggles on
before
You should put a comma before a person name if you're talking directly to them. ex- Please come here,Lily.
before.
put a condom on :)
I am pretty sure you should brush the bottom before you put in the chlorine, but you should check with another source because I am not positive.