Is there a secret to flavouring with herbs

If you're adding inordinate amounts of herbs with no effect, then that sounds to me like a problem with the herbs themselves. If you're using dried herbs, they could just be too old.

To me, dried basil and oregano and marjoram just never taste like much. Fresh, however, they're quite strong. Tarragon, chervil, and dill, on the other hand, do "work" in dried form, and in fact you have to be careful with tarragon. I guess I'd put rosemary in that category too but thanks to some out-of-control plants I've got more fresh rosemary than I could ever possibly use cooking for an army.

For tender herbs, keep them fresh, use them at the last minute and use plenty of them. For the woodier herbs like Rosemary, you can use them at the start of the cooking process but you will probably need to be more restrained with the quantities.

For non-leafy herbs, you might try toasting them a little first. Some herbs (looking at you paprika), don't taste like anything if they're not toasted a little first.

as mentioned if theyre old, then they wont have much flavor. as hard as it seems throw them out every so many months.

i find the best technique in cooking for getting the most out of dried herbs is to use them at the start. since almost everything i cook begins with a base of heating olive oil, then adding fresh [minced/diced/grated/pasted] garlic, and then adding 1/2-1 onion i typically add dried herbs at the point where the onion is half softened. this keeps the scent there so i can continue to add them as needed to balance out their lack of flavor. of course this doesnt work with every recipe but it will help for many.

more important than that, when you add dried herbs crush them in your hands as you are doing so.

I have generally found that herbs (i.e. dried bits of leaves, such as oregano or thyme) impart their flavour best into a water-based solution. Hence I tend to use them in sauces and casseroles based on something like tomatoes, or things that have water in them anyway, like a casserole. I also find that a little acid, lemon juice or balsamic are my favourites, helps bring out the herbs' flavour.

On the other hand, spices (ground powders of seeds and roots and such, like paprika or nutmeg or cumin) release flavour best into fat.

Therefore, when I'm making a tomato sauce for my pasta, I add the nutmeg to the sauteeing onions at the start. I only add the oregano near the end, after the tomatoes are in and releasing their juice.

The best way I'd say to learn with herbs is to isolate them - only use one at a time to get an idea of the different notes that they can add. Also try to add them at different points. For example, parsley is only added at the end where rosemary tends to work well added near the end. Similarly some herbs work better when boiled with other ingredients where others are more suitable for frying. Trial and error is the best way to really get a handle on how to add them properly.

Also, on the whole dried herbs are a waste of time with a few exceptions. Dried oregano or tarragon are OK for example - although different in taste to the fresh ones. Use fresh ones if you can ideally.