Voting for a different party in the primaries? Make sure you can.

"In most states, only voters registered with a party may vote in that party's primary, known as a closed primary. In some states, a semi-closed primary is practiced, in which voters unaffiliated with a party (independents) may choose a party primary in which to vote. In an open primary, any voter may vote in any party's primary. In all of these systems, a voter may participate in only one primary; that is, a voter who casts a vote for a candidate standing for the Republican nomination for president cannot cast a vote for a candidate standing for the Democratic nomination, or vice versa."