Help getting back into the swing of things

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I played a lot of WoL early on, and stopped for quite a long period of time. I've been wanting to go work on mechanics, but have no clue about builds nowadays. So when I ladder, it's sort of a coin toss whether I win or lose. I placed Silver, Protoss.

I was very comfortable doing 2gate/3gate openings against pretty much everyone, but my friends have been telling me that if I don't FE, in most games its pretty much an auto lose. What would you suggest I do for each matchup? I'm still really unsure when to stick the mothership core in there as well. Since I sort of trained myself to never stop building workers, and I usually dump all my gas into stalkers.

Any tips would be greatly appreciated!! =)