This is only a guess, but this being your first project I'm thinking you might not have much experience with a soldering iron.I would practice up if possible ,on an old board from an old VCR or radio.(Don't pull apart your families VCR for this.)
The most important issue in getting good solder joints is having everything clean.That means nice clean copper on the board and on the ends of the parts legs(resistors, capacitors etc.) that stick through the board; a clean, tinned tip on your iron is also a must.(That just means having a coating of solder on the the tip of the iron.)
I'd also read the skills you need articles located at Aron's home page.Good info. there.Good luck with your build!