I just did my very first confession not even two weeks ago. I was a nervous wreck, and ended up not having the… ahem… best confession. THEN I was so upset with myself, and had such a lack of peace that I drove out of my way to find another parish with confession during the week to finish up what I had not said that Saturday. It wasn’t that I went in intending to not say everything, I froze. As in drenched in sweat, light headed, spinning, dizzy, stuttering - all this because I didn’t prepare properly. Talk about learning a lesson the hard way!
SO… my advice is this: PRAY beforehand. A LOT. If you rely simply on your own ability to follow through you may find that things get very difficult. Not that it is easy to admit how we have behaved… I confess that I didn’t pray about it like I should have, thinking “oh, I know what I need to say…” and that was a dreadful mistake. Pray for strength from the Holy Spirit, to be open and honest about the state of affairs.
Remember that you are confessing to God, and the priest is there in Jesus’ place. God already knows what you have done, so you aren’t really hiding anything if you conceal something. And if you conceal on purpose, the absolution isn’t there. Not being willing to confess it all is a symptom of pride (speaking from experience here) and means you are lying to yourself about the honest condition of your soul.
Going through a list to help with an examination can be very helpful. Reading things can jog your memory about areas in which you have failed.
Realize that the priest most likely doesn’t want an exhaustive, detailed list of everything done in your lifetime. General statements of “I’ve lied on numerous occasions” will cover a lot of things, although you may of course have a specific thing in your life that needs to be mentioned. Also, barring you being a mass murderer in private and on the FBI’s top ten wanted list, it is highly doubtful that you are going to say anything the priest hasn’t heard. Many times. I think I actually had a form of pride that I was so awful and just couldn’t admit to things, even though I’ve actually had a very tame life. Well, all have sinned, and the priest knows it. Let me say, I have a whole new respect for the priesthood just in this area - how difficult it must be to hear people confess their sins!
Again, I can tell you from personal experience, that getting it all out feels WONDERFUL afterwards.