if its not your pedals/chainring bolts/

Check the Stem/then seat post

Then check the BB

WD-40 Is worse than no lube in my experience. its just vegetable oil in an aerosol can, i'd sooner bust out bacon grease Jar

And from what i've heard From more than a few mechanics is that lubing the BB spindle will not make REAL difference +/-, providing the cranks are installed properly, some of the wrenches at the shop i work for do some don't.