You are not alone. I have been studying how to get a boarding group since day 1, and when I finally had my chance, I was having serious anxiety. But I needn’t have worried - using @bebe80’s instructions, we had a 100% success rate on our three days attempting (I highly recommend you have at least 2 days reserved at HS to minimize the stress).
Also, here is a poll I did back in October. Only 6% of respondents (4 people out of 66 respondents) had a 0% success rate getting a BG, and only 13% had a less than 50% success rate. So if you have 2 days (4 chances - 7am and 1pm), even if things go wrong one of the times, you should get one at a different drop.