Hi Nuno,
Here is a quick run down on what I am currently using to foil baits, it is by no means the only way or the best but merely what I have settled on so far... I want to try embossing/leafing but have yet to make the effort or buy the materials.
I use a Aluminium tape, generally found in hardware stores for plumbing repairs or for ducting sealing. Some electronics stores may stock it for RF shielding. It has a good adhesive and sticks well.
The best tape is the thinnest you can find, it varies between brands. The thinner the foil the easier to work and smooth out any wrinkles, convex curves are a challenge but you will learn your own limits and the tape's with some practice. Relief cuts may be needed or they can be designed to fit your lure's overall look. Once again the thinner the tape the easier it is to cover seams/joins with epoxy or the finish you are using. Hence the reason I want to try leafing as it so thin.
Trace the outline of your lure, make sure it is a little bit oversize to go around the curves. Cut out the shape and apply the tape to the lure, use your thumb to work the tape down the center/lateral line of the lure, the slowly stick down the rest a little at a time. I use a hard plastic rod that is very smooth to work the tape further. When finished a cast iron rod can be rubbed over the Aluminium tape to get it to really shine.
It takes practice, after a few baits you will be confident and producing a better finished product.
Here is a 100mm hand carved wooden minnow using the above technique ( I produced the scale effect using the knurling on my exacto knife )
Here is a flat foil finish on a diving minnow... 170g & 265mm long.
Another flat finish on a WTD minnow... 90g and 200mm long. ( I added the lateral line in the foil )