Here's something I just posted in the beginner's forum that is worth repeating here:

As soon as you take stuff out of the box, it will never go back the same way, and things get lost VERY quickly! So here's a suggestion: (Note: this advice goes for the ENTIRE building process, not just the first few days)

Lay the box top along side the box. Take things out of the box, look them over (Feel, smell, taste or whatever else blows you skirt up) and return them to the top of the box.

Get in the habit of moving things from one box to the other any time you need to sort through things - That way, anytime you need a part, it will always be in one of two places - Either the box top or the box bottom.