Xcom enemy Unknown as well as Enemy Within have a feature that will insure that your unit always misses its first shot on some enemies unless you have 100% hit chance. As well the game will push there units far into the battle field before it is their turn in the rotation. This in my mind is just the game designers way of putting a big boot where it doesn't belong on game players.
Took me four try's just to get a good start on this game! Some tips: up grade fire power and shielding fast, and be careful on missions don't go to fast and look everywhere! EXTREMLY repetitive in soundtrack and scenery! I did like that they slowly mix in the different lvls of aliens. focus on getting engineer's and setting up satellite uplinks and to start off use steam power. always go to the most paniced country when there are abductions. and don't lose on any missions. if it looks like all your soldiers are going to die abort mission! try and keep your highest raked soldiers they have the best traits.