I'm sorry for writing one reply after another, but I've got some really useful information. I went on a deep search of cosplay DIYs and all the stuff which is connected with this topic. I want to share it with you, in case someone would like to sew their own sexy costume, too.
Here is a good
video with sewing basics.
Here is a comparison of sewing machines, if you are looking for one.
And finally a nice
forum with some useful tips and tricks on making costumes.
I really hope it would be useful for someone