Ever wondered with of God's rules to follow?

I'm doing a 90 day Bible read and in Leviticus 19 there are many rules. Some are easy to understand and should be followed, but others I kinda wonder about...
 
"Do not cut the hair at the sides of your head or clip off the edges of your beard".
 
"Do not cut your bodies for the dead or put tattoo marks on yourselves. I am the LORD".
 
"Do not degrade your daughter by making her a prostitute."
 
Do you just pick and choose or is there some other reasonable way to know which rules to follow? I'm sure it is an issue of old testament before the God of grace comes into the picture, but it gets a bit complicated. If you can justifiably throw out one verse, can you throw out all of them?
 
What do you think?

For more GodSpots - 37stories Enjoy!