Having a few things you can rely on to keep your mind focussed correctly is vital. The less, the easier to remember, so i recommend one mindset to remind your self to live in if you find it hard to approach or converse with a girl you are trying to seduce.
Have fun - that is the mindset. It eases the burden of responsibility and outcome and allows you to enjoy the process (as much as possible!) Once you have this new found relaxation, hopefully your seduction will flow more smoothly. If it doenst though, I always like to have a few fallback tactics to employ. In the PUA community these are called routines, and you can google that to find one or two that work for you.
Personally, i always use the same few. If there are two girls you've approached, ask how the know each other. If it is one girl and you are comfortable with each other, then go for the 5 questions routine. Try it, it ight help you to seduce hot girls. If not then see what you think of this live seduction in progress, in the field, captured on video below or check out a resource such as http://en.wikipedia.org/wiki/Seduction_community.