Quetex, I strongly suggest to buy a good food magazine every now and then. In my country and in France, many magazines have an extra seasonal issue with recipes only. I would guess it's the same in your country. That is such a good source for trying out the modern way how different seasonal product work together. I just bought a fall issue with 100 exciting top recipes for 8€.
Sauces are so important. It's the final finishing touch of a dish. It ties everything on the plate together. I have to admit that it's imo probably the most difficult thing in cooking. The wrong sauce will simply kill a dish. The right sauce will do magic. And, most of all, a dish without a sauce is not nearly finished.
The days of standard heavy sauces from old cookbooks are so over. Today, cooking is about light but very tasty, including sauces and jus. That's what you'll find in magazines. On the other hand, it never hurts to have a quick browse in the dusty old cookbooks to learn something about classic techniques. You will discover that many modern sauces are contemporary, easier and lighter versions of the classics.
A very good book on spices with a good deal of recipes; Spice Market by Jane Lawson - Murdoch Books Pty Limited