Look, i'm not trying to sound offensive here, this is actual advice that I would advise every support main take.
Before picking your support **Please** look at the team comp and see what is missing if you're 3-5th pick, instead of just playing a heavy AP support when were a Heavy AP team with no frontline.
Before even playing support please find out if you're good with things like engaging fights and important skill shots, because if you're not then stick to easy supports like soraka or janna, instead of taking Blitz or Thresh where their main form of initiation is their Q skillshot, if you miss every one of your Q's in lane it just makes it harder for the adc.
Edit: For those of you saying "Why is this only directed torwards supports and not other roles". The reason is the fact that I have to lane with you Support mains because i'm an adc main, and lane matchups are a really important factor that can have a positive or negative factor on how lane goes. If you know you're bad at skillshots like a blitz hook, but still pick him, not only are you making yourself look bad but youre making it a lot harder for you lane partner.