Speedcubing tips!?!?!??!? (Only for those who actually speedcube)?

I use the petrus method and can't break the 30 second barrier. I don't understand the symbols for the algorithms very well (F,L,R,B ect.). I need tips on how to prevent delays between algorithms and I need tips on how to read the algorithm symbols. (I don't want to be linked to another site and I will give the best answer to what helps me the most so be descriptive).