If you are praying the rosary and having a hard time noticing any coincidences or answer to prayer then here are some troubleshooting questions to help you "tune in" to God's frequency.
First, examine your conscience. Sin, especially mortal sin, acts like radio static when you are trying to hear God. When I'm having a hard time discerning signal graces, its almost always because I need to go to Confession. Go to Confession and then try praying the rosary again. This practice has never failed me. For a biblical understanding of Confessions see when Jesus gives the Apostles (and thus their successors-bishops/priests) the power to forgive sins in Mt 16:18-19, Mt 18:18, & Jn 20:22-23.
Second, signal graces seem to be stronger when you are doing some sort of spiritual reading. Its like giving God something meaningful to work with. Try reading the Bible, a devotional, or a spiritual book. Then God will use other things or people to mimic those good spiritual topics. The parable of the sower explains this idea (Mark 4:1-9).
Third, brag on God. I've found the more I praise God and share the miraculous things He's done in my life, the more he rewards me with signal graces. The parable of the talents explains this idea (Matthew 25:14-30).
