Prepair. It's Chess. What can possibly go wrong?
Concentrate on WHO. Then WHY (if You have time). Then HOW. Then WHAT.
Precaution: When inside a fight, concentrate on taking initiative. Drop some points to buy the first turn. Usually there is no any justifiable reason to attack second, unless that's a recon fight.
Prepare for close distance combat.
Grab all the available ammo. Yes, I know it's HEAVY. Grab it all! There are times when You want it MORE!!!
Equip Yourself. Come packed and loaded.
Be a princeess of the Universe. Inside Your body, soul, heart, spirit. Shine.
Eat. Rest. Sleep. Stay in form. Fit. Do benevolence to Your own body.
Hide all the tech. Mobile. It's art. Or at least it has to be.
Analyse other people fight data. Build. Man-up!!!
Study reconeccance hacking. Very often the only thing between You and the precious data is Windows XP. Yes, it's 2019, but many firms still use WinXP to get it for free. Heavens, it's often not even a database, but an uncoded Excel file. Sometimes You might need this simple piece of information like air. In fact, forget about hacking. Just carry a USB flashcard in Your bag. Use it, drag and drop. Assume that Your oppornent wants to kill You. Do Your worst. First.