They may become more defiant and want to do things their own way which is normal at this age.She may be shedding her "baby" stage meaning she wants to be a big girl and dress herself and possibly want to wear make up.
Normal behavior will be differnt with each 8 year old girl. Most however will be playing with their peers, thay may also be trying to adventure out on there own and become a little hard to handle trying to gain their own independance.
At eight little girls should be interested in playing outside or even playing dress up. Most little girls at that age may show intrest in make up or other things that they may see their mothers or other older women do. Wanting to learn to bake or even reading age appropriate books is normal.