Q: What do you do with field notes after you're back from the field?
A: Keep them. Forever.
My dad is an attorney, and there is a similar problem in law: a full paper trail documenting all aspects of a given legal case is required to be kept by the attorney for 10 years. My dad does get a bit of business, so growing up I was a bit confused about why we had so many banker boxes filled with boring legal documents sitting in our garage. About once a year, he'd go out and dispose of whatever case files were over 10 years old. It's a pain, but it's got to be done in order to "cover your ass", so to speak. Fortunately in science we don't quite have that same level of paper to churn through - in a decade of research I've filled up about a dozen field notebooks and a half dozen moleskine lab notebooks - it won't even fill up a single banker's box. But here's the catch: in science, there is no statute of limitations. We've got to keep our notes forever; the best way to go about this is to literally deposit your notebooks - or a copy of it - with the institution housing the material the notes are associated with. Disclaimer: I still haven't actually done this for UCMP, but have transcribed all the notes for individual specimens that are now in their collections - so they have all the information, just not in notebook form. This way, in case your house burns down, or your cat pees on your stuff (it happens, trust me) there is another copy someplace. An even better idea - scan your notebooks to pdf; I did this with all of my notebooks before leaving NZ.
Here's all of my notebooks - see, you don't throw them away when you're done. Safeguard them!
Traveling? I always carry my notebooks on my person - I NEVER trust the airline (or shipping company) to do the right thing. So, my bookbag coming to/from New Zealand was a bit heavy, as I literally carried every single one of my notebooks on me rather than risk the fate of losing them if my bag was misplaced, stolen, or just got wet or damaged. I once had a partial fossil baleen whale skull from a tidepool in Santa Cruz - shipped as a checked bag (well, cardboard box) - sit on the tarmac overnight in the rain at SETAC on my way back to Bozeman for spring semester. Now, the skull was fine because 1) it sat in a tidepool for probably a century and is fairly immune to water (it was covered in algae and barnacles and smelled HORRENDOUS when it was delivered the next day, but that's another story) and 2) is in a concretion and practically indestructible. But say that had been a non-waterproof duffel bag with handwritten notes in it? Sayonara! My buddy Lee Hall has lost his checked luggage while flying to Canada twice (once at the 2006 Ottawa Society of Vertebrate Paleontology meeting, including all of his nice clothes) and luckily got all of his stuff back the first time (can't remember if he got his bags back the second time). Losing clothes (and field gear the second time) is frustrating enough - but it could happen if something really important is placed in checked luggage.
Moral of the story: don't trust yourself to be the only steward of data. Scan it to pdf, email it to the host institution (or print it out and snail mail it to them), upload the pdf to cloud storage if you're really paranoid.
Q: What do you do with fossils after you're back from the field?
A: A bit more nuanced than the answer above. I'll explain more.
Presumably you've followed my advice from the prior post and have started using field numbers for fossils - if so, great! If not, go read it again and reevaluate why you want to be a paleontologist - professional or otherwise. Now, after returning triumphantly from the field, your first interest (aside from taking a shower and sleeping) might be to start preparing the fossils. And that's fine - this is the stage of the process where you can paint numbers onto a smooth exposed surface. I recommend sticking with archival materials - use acrylic white paint and an archival micron pen to write with. Now, if you still need your field notebook - or if your notes are in shorthand, as mine are - you're going to need to transcribe them somehow in order to keep that data physically associated with the fossil. You can write out the field number, collection collector, date, identification, location, and stratigraphic level onto a small sheet of paper - these are the basics, and many museum databases do not give the opportunity to include intra-formational stratigraphic data, so including this information will help future researchers interested in higher precision data use your fossils.
Or, if you're more organized and prefer something standardized, you can use pre-made collection sheet forms that are small enough to fit all relevant data that 1) links the field number and museum number and 2) also includes more detailed information that cannot easily be included into a database. I'll admit I got the idea for mine from seeing these sheets in UCMP collections filled out by marine mammal paleontologist Ed Mitchell (the guy who named Valenictus, Imagotaria, Allodesmus kelloggi, and Llanocetus denticrenatus) and used a similar approach.
Some other tips:
-Don't write field numbers in permanent ink, and don't write directly on the bone; according to work done by former Museum of the Rockies artist-in-residence Michael "Spiff" Holland, if it ever goes on display the only way to get around permanent ink written right on the bone is to paint over it, with a matching "bone" color. A swatch of white acrylic paint is fine, and can be removed if you so desire.
-If you prepare multiple fossils at the same time, make sure you keep something clearly indicating what field number belongs to a particular specimen until the time comes when you can paint a label onto it. Preparation is the easiest stage at which field numbers can disappear. I tend to keep incompletely prepped fossils sitting on their actual field ziplock bag until they're fully prepped and labeled.
-What if a fossil is too small to write on? Use a smaller plastic bag and write on that! There are archival tiny plastic bags (and yes, they do resemble the ones drug dealers use) that can be used. If a fossil is super super tiny, I use two-part ~250 mg pill capsules and cut out a tiny rectangle of index card and write the field number in archival ink. And because the capsule is still tiny, I then put that inside a smallish bag and write on that too.