"How do I tell if God is saying something to me?"

What I hear you asking is "How do I tell if God is saying something to me?" I believe there are three important things to talk about in regards to that question.

First, you (meaning you as in everyone) have to take all the evidence into consideration. Like you were saying, God speaks to us through everything in our life. To ignore one way that God is trying to speak to us isn't smart. The Bible, prayer, logic, feelings, people, nature - all of it has to be taken into account if you're seriously trying to hear God's words to you. This point can be summed up as: "listen hard".

Second is the supremacy of the Bible. This is difficult to talk about because you can't just objectively read the Bible and go from there, checking all the other things you think God's saying to you against what the Bible's saying (which you've determined with 100% objective accuracy), and then throwing out everything the Bible's not saying, and going from there. But who can interpret the Bible in a purely objective way? Everything in our lives and (hopefully - and we have to pray for this because only the Holy Spirit can truely give insight) the Holy Spirit comes alongside us and gives us real insight into what the Bible's saying. And that insight might not be the same as someone elses', since everyone's life is different and the Holy Spirit certainly reveals different things to different people over time. It has to be said that there are definite limits to this variety, but that's not the point I want to focus on. All of this comes together to say that we can rest on the Bible as God's words to us and use (what must admittedly be our interpretion of) those words as a check to make sure we're hearing God right.

Third is something I touched on in the paragraph above, and that is that you have to listen to the Living Word, the person Jesus Christ, as the final word. That is, regularly communing with God and seeking to hear His voice is of the greatest importance if you expect to hear His voice. Without the presence of His person in your life, you have nothing solid to base your choices on.

Matt