Well yesterday i succesfully picked up 2 girls on the dancefloor. I just came to them and asked why they were dancing alone? They claimed they werent to which i replied "well i came here to save your day" --> "Confident guy..

"
then i just took them to the bar.
If the dancefloor is really crowded and there are guys grindin the girls all over the place then i just suppose you gotta do some dancing and talk to them --> take them out of the dancefloor when the song changes.
Telling them that you wanna do a drinking game or something will do good to grab their attention and makes it easier to take them out of the dancefloor.