Where's the money? From whom does your representative or candidate take campaign money? How do they spend it? What percentage of money does a candidate take from political action committees versus individual donors? The PACs with the most money are often funded by corporations and interest groups. "A reliance on PACs, versus individual donors, can tell you something about a candidate’s institutional support versus grassroots support," Giwa reports. "A higher percentage of funds from PACs means a candidate’s donor money comes mostly in fairly large checks, as opposed to donations from individuals. A higher percentage of individual donations, on the other hand, is a sign of grassroots enthusiasm about the campaign."
What do the numbers mean? Campaign donations are the lifeblood of a political campaign; they can't air ads or pay staffers without it. The more competitive races tend to attract more money; a race listed as a Toss-Up by the Cook Political Report will likely be well-funded on both sides. Money tends to win races, too; with some notable exceptions, the candidate who brings in more money is more likely to win. But Giwa notes, "Money is important, but it’s not the only factor."
What about the issues? Candidates address issues on their websites and in press releases, but some candidates' claims can be misleading, so look at nonpartisan fact checkers like FactCheck.org and Politifact. Another good source is the League of Women Voters' Vote411.org project. The League reached out to every state and local candidate for office with a set of identical questions and recorded the answers in a database.