Whenever I teach a writing class I always start by saying "there are (let's say) thirty in the class. Two of you will make it." If you hear that and go "Jesus, those are terrible odds. How am I gonna compete with that?" you're dead. However, if you say "Hmmm? Me and who else?" then read on. You've got a chance. And here's the good news: Those odds just went from 15-1 to 3-1.
You have to believe in yourself first if you ever expect anyone else to.
More good news: If you are good you will be recognized. It may take some time but it will happen. Remember, readers WANT to like your script. They're BEGGING to like your script. But the key is to stick with it. Don't rely on one spec. Often times I'll meet young writers who will say "I wrote a great FRIENDS four years ago and can't get an agent." L-O-S-E-R-S. It might take five specs, it might take ten. But all you need is one person somewhere who sparks to your material. And once you're in you're in.
In future posts I'll be giving tips on what I look for in a spec. In the meantime, start writing. You're already beating the odds.