Hey, I'm also currently playing and there are many things I have learnt. Firstly, if you want to finish the side quests as well as the main story like me, keep doing side missions as you find them because there are certain missions that may interfere a certain side quest and you may end up failing the secondary quest. There are three main regions at the start of the game, Velen, Novigrad and Skellige. Like I said, don't leave the region without completing all the secondary missions as well as the main quests. Some secondary quests will unlock after you complete the game, so you'll visit those places again in the future. Make sure you keep leveling up by doing Witcher Contracts as they pay well and give more experience. Keep saving the game at the start of any mission as well as in between, especially after you defeat a boss, because it may be tough to beat. As for better Armor and Weapons, find a good blacksmith, there's one at Crow's Perch, inside the Bloody Baron's fort in Velen, it will be one of the earliest ones you'll meet in the Velen Main Story. Keep looting buildings and random loot as some of them may contain better Armor Diagrams.

Stay away from the damn spider monsters.

Hi I’ve been playing since release and I’m only on my second play-through but I’ve got around 700hours in game, when first starting out best thing to do is do some side quests and contracts and then do the main story line, keep in mind the main storyline is a long one covering many regions so when certain quests for let’s say they mention “ we can meet you there?” Or when they give you multiple locations and missions to go to take that as a perfect opportunity to pause the main story and continue discovering the world, even with 700 hours I’m still finding new things and even quests to do. Also do the dlc at the end of the game you can do hearts of stone when the quest line “ battle preparations” activates and do blood and wine when you have completed both the main game and hearts of stone!

Good luck 🤞