Once you have mastered getting the back cover off the Z30 you will see that the SIM and microSD slots are very clearly marked - with the SIM having a large orange diagram beside it and the microSD card having a blue one. These diagrams show which way up the cards must be inserted via the cut out on one corner of both cards.
Both the microSD and the SIM card go in with the contact points facing upwards - just to clear any confusion, and then you can replace the back cover, meaning you're good to go.
It may not be rocket science, but it is nice to see BlackBerry making the process pretty much fool proof with their colored diagrams, which I don't believe we have seen on previous BlackBerry 10 devices. I tip my hat to you BlackBerry!