By all means, use recipe books, especially for suggestions, but don't get too bogged down. Just remember the basic proportions, and you'll do fine! If you approach cooking as an adventure, you will be much more likely to venture out into unexplored territory! Do not be afraid to try small variations in proportions, or much greater variations in tastes--remember that what tastes great to one person will be icky to another, so don't be offended if someone, somewhere doesn't like your creation--someone else will absolutely love it!
Also don't be afraid to take those old children's classics and revamp them for more sophisticated tastes. Instead of plain Nilla Wafer banana pudding, how about spicing that up with gingerbread instead of Nilla Wafers? What about adding banana liqueur, or livening it up with orange or lime zest, or adding nutmeg? Or a tiny hint of chipotle? In the kitchen, anything goes--although sometimes it goes to the dog!