If you’re serious about twitching and keeping track of every species you’ve seen, start keeping good lists. When we first started birding, I did not always keep good lists. A good list has a date, time, approximate distance, location, list and counts for each species you can identify. Our early lists were not always like that.
In fact, a good way to keep your lists is to put them on eBird. Actually, I didn’t do that either for a lot of our early lists (I’m the designated eBird-list-keeper). Because of this, I spent about ten hours last week reconstructing lists and times based on my luckily accurate camera times and submitting lists to eBird that I just forgot about! I did that so pretty much all the species we’ve seen are actually recorded on eBird. Don’t make the mistake of keeping bad lists!
Now I’m much more careful about our lists. Speaking of lists, even if you are excellent about updating eBird, I suggest also keeping a separate spreadsheet with species name, location, and first seen date, using the eBird downloadable checklist for the species names (and family and order). I believe in redundancy, and having a good offline and easily editable spreadsheet also allows you to manually update to the latest taxonomies. That way if two species are merged in your favourite list, you can copy and paste the entry to another sheet so you don’t lose that observation. Then if those species are split again, you can move it back.
I also keep a photo record in a single PDF file (one file per country) so that every tick can be easily recalled. It’s also a fun way to easily browse all your sightings in one shot. We’ve taken pictures of every bird we’ve seen except three. Every time I put a picture in the book, I re-consult the guides to verify that we made the correct identification. It’s just another level of accuracy in twitching.
When keeping your lists, don’t forget to use a good pen with waterproof, acid-free ink so that your lists don’t degrade or wash away in a little rain. Art stores are great places to get these.