That depends on where you live.
If you live in a solid red state Then, no, your vote doesn't really matter. These states will go (R) regardless. Same if you live in a solid blue state.
The states that will matter will be Ohio and Florida. Republicans have no path to victory without both of them. Win these states, and you have a good chance of turning a handful of purple states red as well.
But first our candidate has to survive the primaries where populous blue states like California and New York play a huge role in selecting the Republican candidate. Add in Illinois, Pennsylvania and the liberal Northeast and it is easy to understand why a serious candidate may wish to steer clear of social issues like abortion and gays. These issues may play well in the South but Republicans aren't worried about winning here. They already have.
I’m in Texas so you’ll probably say we’re staying red, but states are flipping faster and faster.
The liberals took over California in about 20 years (finalizing with Reagan’s amnesty). Colorado only took about 10 years.
With millions of illegals being added to the electorate now, Texas is next (and probably the last one they need). In 2012, Bexar County (San Antonio), Travis County (Austin), Harris County (Houston) and Dallas County all went blue. That almost covers the majority of the state’s population.
Scary stuff...