CAD programs can be a point of where mistakes are made (a contradiction really, because they are there to ease/speed up design for us), like pinout, symbols or footprint mistakes.
Double check everything. And really learn how to use your tools. It applies to every tool, I've used Eagle, Altium and Mentor Graphics in similar environments and all have their individual quirks.
For example; I did a DRC of a PCB in Mentor Graphics and it said no errors. What I didn't know then was it only checked the area currently in 2D view visible. I guess it can be considered as a feature, but it was really annoying to find out afterwards it worked like that.. (luckily, it was only 1 GND via that went through an inner layer trace).
I was used to Altium/Eagle, which check everything on DRC, and generate a report about it (although Eagle hides errors on hidden layers, but atleast it says so).
Troubleshooting Windows is always annoying, and I can only recommended staying away from trial software (DRM = JUNK/malware), Internet Explorer, illegal software (cracks/keygens), etc. Luckily these days, there are a lot of tools out there that are free or obtainable if you say you're a student (usually in a form that is limited in 1 way or another).
Computer hardware can always sporadically fail, which is particularly annoying. In all cases (hardware/software trouble), google is your friend.
Another example: Firefox/Chrome and FLASH is so unstable. I started hating any website that uses FLASH, but it seems a bit of a necessary evil (especially if you're a youtube junk like me). Last update (where they changed the layout again), every video on Youtube stopped playing after 2-3 seconds and says "Playback error". Recommendations of Youtube? Clear your whole browser profile. No! Damnit, that's not a way of resolving problems. That's like saying, your windows is getting slow, just reformat everything and try again. Turns out a 3rd party plug-in Youtube Center (for Greasemonkey) gives the possibility to disable DASH playback, which YouTube uses to crap-ify their playback (like it stops buffering the whole video, only buffers 2-3 seconds ahead etc.).
Going into something that particularly annoys me is the way "big" part suppliers can be towards consumers (students/hobbysts without VAT number).
Apparently here in the Netherlands the only shops where I can order for any amount I want (plus paying for shipping) without a creditcard, are Conrad and Distrelec. And both of those shops haven't got a (Serious.. Cyclone 3, Spartan 3) FPGA for sale, or any unusual part.
RS don't even deal with any consumer customer in NL anymore (meanwhile they are advertising DesignSpark very hard towards hobbyists/students/etc.). I asked them via mail once and got the response back "That's our policy".
Farnell requires at least 50 euro's and paying upfront, which is a bit paranoia. But I guess OK (and Farnell stocks a lot, which is good).
Digikey/Mouser I'm not sure of, but I believe they require a CC/minimum order amount of 75 euro's/high shipping rates.
I remember the RPi exclusivity period. RS and Farnell sold them, and a lot of computer fanatics wanted one! But "normal" computer nerds couldn't order them, because they are just consumers