As ever, the relevant volume of Thom is your friend, and the Confuser is your confessor. Read the book, making notes as you go. Work through the examples at the end of each chapter. Then try the Confuser exam. Repeat until you can score at least 98%.
As for specifics, post exam, my experience is that thunderstorms are very bad, and if the weather is murky enough to make you think you really ought to be being paid money to go out and fly in it, then unless you have the bits of paper to prove you can be paid the money to go out and fly in it, and someone is offering you lots of money, then your best bet is to knock it on the head and do something else.
The best sort of clouds are the sort you can fly a loop around....Cumulo-Loopus.
Best of luck with the exam.