Be careful with your choices. They matter. The problem is you can't just quicksave before making a choice and reload it if you don't like it. You might not see the outcome of that choice for a couple of hours and that's a lot of game time to lose. What seems like the obvious choice usually isn't. Dodge is your friend, you will learn to love it. Quen is your friend, dodge won't mind if you cheat on it with Quen. No matter how much you may want to, you'll know why when you get to it, you can't bang the herbalist. Stop looking for a way to do it you'll just waste hours like I did. She's just a tease. Cows have much bigger friends. The tax man will find you. Find set armour and weapons when you can (Griffon, Ursine, Cat and Wolf schools are all in the game now). If you see a large monster that is higher level than you, don't piss it off.

Start out on death march. You'll earn all the achievements in one play through. Also, put all your sign power into quen. Both versions of it are completely overpowered.

Explore like crazy. Embrace how expansive this world is. Don't turn up the difficulty for your first playthrough because the combat has a bit of a learning curve. Play Gwent whenever possible because it's the greatest mini game of all time. With decisions carefully because unlike Bioware or Bethesda game a where you can quick save and see a choice's outcome immediately to decide what you want, it may take hours or longer to see what impact your choices have on the world and its people.

Play the side missions

Do [b][u][i]EVERYTHING.[/i][/u][/b]

Start off on the lower difficulties, and then ease yourself into Death March.

Play on either the second-highest or highest difficulty. You'll thank me later.