I have to admit that I've never understood the US "voluntary voting" system. In Australia, it's mandatory.
Many people are uninformed - which is a real pity because it is fairly easy to become informed.
When I was 18, I made appointments to visit local politicians and party reps from the various political parties - with a pre-prepared list of questions.
I have to admit - this wasn't my own idea! It was suggested to me by 3 extrordinary gentlemen - very long term family friends, all politicians at Australian state and federal level, and all 3 in different political parties. They helped me to come up with the questions, refused to be the persons I asked (because they said that I needed to get perspectives other than theirs). They said never vote for a person because you like them - and cited examples of con men who make it their business to be likeable.
They also told me how politics works. When a candidate makes a promise, do a bit of digging. To get anything done in politics it takes a few years. So when you see a pollie promising something, and low and behold they get in and it happens - look into the background. It's been going for a few years.
That's the main thing to remember - in any democracy, things don't happen quickly, so promises are made based on "inside knowledge"
The best way to determine your voting is to become familiar with the objectives of the parties, their values, and strategies, and decide based on how these match your own.
Also look at a candidte's track record for representing the people. In our last election, I voted for a candidate from a party I would never normally endorse: because the candidate had an excellent track record as our representative. He had already been in one term, and was always there to open school fetes, had alot of "curbside offices" (where he would literally go to a shopping mall, etc., set up a desk and chair, and be available for anybody and everybody) and didn't promise grand things - but made sure that the important things were done. The interesting thing is , he's rarely in the "big" media, and I've never seen or heard of him making public comments that belittle the opposing political parties.
Being informed about politics is as easy as looking around your local representative area.
Yes - your vote is your voice. I do believe that if you don't vote then you have no right at all to complain about the people who get in. It's like if you go to a restaurant and let the waiter choose your meal. If you don't like what you were given, then too bad - you gave away your right to complain when you made the decision not to choose.
That being said, people who don't vote aren't responsible for the "bad" things that happen - just the same as people who do aren't. And sometimes, something that is "bad" now, in 15 or 20 years will, in hindsight, turn out to be the best decision that could have been made.
Women worked hard to obtain the right to vote - and in some countries women still can't vote. If you do truly believe in womens rights, then not voting is a slap in the face to the first womens rights movement - the Sufferage.