Which precautions should a newbie like me do when exporting keys from an Bitcoin Core wallet to an Electrum wallet
Before you begin any of this, I recommend you backup your .dat files just in case something goes wrong.

Your wallet.dat file is located at %APPDATA%\Bitcoin\wallet.dat. Make a copy somewhere safe until this operation is complete.

You're going to want to export your private keys from Bitcoin QT and sweep your private keys in Electrum and you should be golden!

The process of dumping your private keys require you open a console (Bitcoin QT -> help -> debug window -> console), unlock your wallet (walletpassphrase "your walletpassphrase here" 600), and type the command dumpprivkey [your Bitcoin address here]. You can then lock your wallet with walletlock.

With your private keys saved now, you can sweep them with Electrum by opening the sweep menu (Wallet menu -> Private Keys -> Sweep), entering your private keys while leaving the 'Address' field unchanged, and executing the dialogue.

Enjoy your new light-weight bitcoin client.