Hi Nicole!
I see you're brand new here...welcome! You can try using the search box to put in a specific term, and also, take a while to familiarize yourself with the boards. There's a LOT of info here, and it can seem overwhelming at first, but looking through the topic headings and utilizing the search box should get you started. I'm not an illustrator, so I can't offer any specific advice on portfolios (but you'll find there is an illustrator section). I can give you the short answer on rhyming PBs: they have to be perfect--rhyme/rhythm/meter + great story arc & concept--to sell. Rhyming PBs that are well written will never go out of style, IMO. But writing in rhyme is its own unique skill set with a steep learning curve. There are some excellent topic headings about rhyme if you're interested in learning more about writing rhyming PBs.
Again, welcome!