When you have your first child, you may end up buying lots of outfits that look cute or pretty and not really thinking about when the baby will be wearing it.
I made this mistake with my first child, buying her lots of pretty dresses and matching hats, to find out that she hardly got to wear them. Often babies spend much of their early days in sleep suits and comfy, practical clothing and you may also find that you are having to change their clothes a number of times throughout the day. By the time there was a suitable event in which my baby could wear a pretty dress etc, she had out grown it. I learnt very quickly with my second child!
Buying second hand clothes really can save you a fortune as the little use they get out of them means often second hand clothes are almost as good as new.