Dear Crispin,  

You most probably have some idea as regards the type of priest you think God is calling you to be, and you have probably felt him attracting you to something concrete, such as becoming a diocesan priest in a parish, or a missionary, or a contemplative.  

If you are only thinking of the "priesthood" and nothing more specific, it is probably safe to imagine that it is the diocesan priesthood that you should look into. In this case the person to contact is the vocation director for your diocese. He will speak to you and be able to make an initial determination if the call you feel is real. Don't be surprised at this; even though we feel the attraction and conviction in our hearts, the call has to be discerned by the Church for it to be valid. The vocation director himself or your bishop will know the seminary to send you to if they see there are definite signs of a call.  

If your thoughts are still vague but inclined more towards religious and community life, you should ask the vocation director for a guide to the different religious orders. Reading this will give you a lot to go on, and perhaps you will discover a particular group you want to get in touch with.  

But keep in mind especially that God is the one who calls, so pray trustfully to the Holy Spirit, knowing that he will lead your steps if you are generous with him.  

God bless.