Where can fossils be found? Fossils are obviously found in exposed rocks, therefore not covered by soil or vegetation: quarries, mountains, scree slopes, coastlines, ravines, riverbeds... In plains with rare outcrops, construction work offers opportunities: foundations, road widening…. If you target a specific geological stage like the Albian, the Infoterre and Geoportail French portals allow you to consult geological maps and see where the stage is exposed. Google Earth aerial views are also useful for detecting ravines or old quarries that are not visible at ground level. Finally, don't look for the perfect specimen because it rarely exists: if you find a species you don't have, bringing back only one half-whorl is better than nothing!
Provenances. A collection without provenances has no scientific value! When you find a fossil, note the location (e.g., "embankment near the D33-D12 intersection"), its position on a map or its GPS coordinates. Also note the municipality, the type of outcrop (quarry, shoreline, etc.), the surrounding rock (clay, limestone, etc.), and the geological stage. If you know the stage boundaries, note the vertical position, e.g., "Middle Albian, Gault Clay, 1 meter above the Lower Green Sands." If you visit several sites, separate their specimens into plastic sleeves, with the provenance information in each sleeve.
Extraction, cleaning and preparation. Do not attempt to excavate a fossil on site: take the roughly hewn block home, to work on it comfortably. You will find many mechanical and chemical preparation techniques online, more or less effective. Avoid varnishing fossils, as varnish is very difficult to remove when you no longer want it. If you accidentally break a fossil, either on site or during preparation, it's not a disaster: simply use glue to restore it; even museums have restored specimens! For pyritic fossils, I've tried everything, like ethanolamine thioglycolate, but some specimens still deteriorate. The minimum is to rinse them thoroughly to remove traces of salt, detergent, and chemicals. Dry them for several days on a radiator, and then store them in zip-lock plastic bags, which are finally placed inside airtight Tupperware containers. If you envisage professional preparations, you'll need a compressor and a pneumatic hammer like the Venn W224 or the more powerful Hardy Winkler HW-70, or even a more costly sandblaster. These tools are expensive and take a long time to recoup the cost for amateurs, but an association or a club can afford them.
Identification and storage. Identification is difficult for amateurs. Never rely on a simple profile picture seen on the internet! Gather documents, visit museums, read geology journals, consult websites showing species, like mine or ammonites.org, or join a club. If you've carefully noted the provenance and the layer, identification will be possible sooner or later. Label your fossils: if boxes of unlabeled fossils fall or get mixed up, it's a disaster! I use tiny labels that I print on paper, cut out, and attach with gel glue. If necessary, they can be easily removed with acetone or white spirit. You can also write these labels with an ultra-fine permanent marker, such as the Staedtler Pigment Liner 0.05, available in art supply stores. Simultaneously, register the labeled specimens in an Excel file, along with their provenance information. Finally, display the best ones in a showcase and store the others in modular cardboard boxes (folding boxes), which are then placed in cardboard trays (flats), see for instance Krantz.
Ethics. Fossil collecting in France is under threat, as seen in Villers-sur-Mer (Normandy), where it is now forbidden to collect specimens. The two main culprits are psychopathic bureaucrats, who want to put nature under a glass dome and make it inaccessible to the public, and "poachers" who destroy sites and render them unusable for scientists. I saw on the Internet some guys who collected 100 samples of the same species: what for, if not to sell them? Respect natural reserves and private land! Take only a few specimens for your collection and leave some for others. Don't dig holes indiscriminately, especially in roadside embankments, as this is an offense punishable by law. On the other hand, save specimens comdemned to destruction, like in quarries producing road metal using jaw crushers!