God may tell you how pleased He is with you for willing to be used by Him. This will vary from preacher to preacher. As an example, in my experience of being still willing to preach whilst having a miscarriage, God blessed me with so many friends as a result of that very sermon (see Fight The Good Fight Of Faith).
God may also let you in on miracles that happened during your sermon, even months after the sermon was preached (see God's Personal Assurance).
God will also tell you if He is displeased with you. For example, God's Holy Spirit will show you / convict you of even the slightest of pride that may have crept into your heart (because a sermon had gone really well, you had received a lot of compliments, and have taken the glory for yourself). The conviction is often very gentle and private at first. Respond to this, do not delay! Get rid of any traces of pride. If this is difficult, pray about it and ask God to purify your heart. If you do not respond to His gentle and private conviction, the conviction will get bigger and bigger, and God may have to bring you down in public.
God may also let you see and hear of miracles that have happened as a result of people applying what they heard in your sermon (in my experience, this has been particularly true for the tithing sermon (see Healing from a Tithing Sermon).
If you ever feel down about a particular sermon, God may well encourage you through people. You may suddenly hear of someone's life being changed by your sermon.
I have also learnt that God often confirmed the topic of my sermon by making me hear and see other similar topics being preached on radio or TV, or even in lyrics of a song after (not before) I have preached my sermon.
© Elma Larsen. All rights reserved.
Image by Glenn Leonard from nicepng.com