Also make sure you line up on the straight of grain correctly. There are arrows on the pattern pieces that tell you which way to place the piece on the fabric so the bias will be in the right places so that the completed garment hangs right. Very important not to stray away from how to place those patterns on the grain. Also the patterns usually have notches in them that require lineing up with other pattern pieces.
Most garments need interfacing somewhere but the pattern will specify.
I haven't sewn a garment in ages but I do remember McCalls and Simplicity were the easiest patterns. I think McCalls used to have patterns geared to make in an afternoon. I loved those and they really were easy.