Thanks for bringing this topic up. This is one of the skills I'm trying to advance on as well. There are times when thoughts that are not mine that are inserted into my mind that are good and positive that I assume come from my spirit guides. And I also get quite a bit of daily ear ringing that I suspect may also be a spirit guide communicating (the ringing tends to coincide with thoughts and ideas that I have). But its so far a one way communication and I would like to break through and get a two-way communication going. From what I gather, there is not really one way that people communicate with spirit guides as it runs the gamut. It appears that we have to listen to others on what works for them and find a method that best works for each of us. And then like @nocturnes-angel stated, you have to get your "mind right" if you're not naturally tuned for this.
Here's a link from a podcast that I listen to often that touches on this subject. You may find some of the info. and his other blogs useful:
And the same author also offers an online workshop that I have not yet tried but sounds promising: