Any tips? All I basically play is a MD berseker and pray over corpses and throw axes until I die in the next 2 floors. And before I play any magic/spellbook/wizards I want to learn how to play melee-based characters. And maybe how to decipher scrolls before using them. if that's possible.
That's....that's basically all Crawl is at its core. Walk until you find trouble.
Actually playing Crawl is about managing situations and risk. You'll quickly run into groups of monsters that will annihilate you if you don't use the layout, tactics and items to maximum advantage.
So stuff like:
Keeping your combats in corridors so you fight things one at a time.
Learning what gear does to your stats, your skills...and how to "build" a character for success. (Gear sets)
Stair dancing to reduce the # of monsters you fight, and knowing when to retreat.
Separating groups of enemies without stairs as best you can.
Breaking LOS so casters and ranged close range.
Separating groups of enemies as best you can
Prioritizing targets in crisis situations.
When and where items are best used.
Getting "better" at Crawl is about learning to always be meticulous as in combat and as you move around. (Like reading EVERY monster description to know what its innate magic resistance is.) It takes a lot of focus, actually, to keep that up without making a fatal mistake. And it takes a shit load of luck, if you're not cheating, to not run into a game ender on every floor, regardless of how well you play. It takes a lot of knowledge about what's in the Dungeon to survive it.
Without reading the wiki, it will take you....dozens of Crawls to see the branch areas, and each area will probably be the end of dozens of Crawls as you learn the ins and outs of the monster types and traps and stuff. (I.e., learning that you've got to have Poison Resistance for at least two branches, more like 4, or you're screwed.)
And maybe how to decipher scrolls before using them. if that's possible.
It's not, really. Every scroll type is assigned a random, unidentified name at game start. I wait until I have at least 3 of any kind of unidentified scroll. Odds are good that scroll type is beneficial, so I chance reading it. Odds are strong too that it's a scroll of identify, since those are given out early on. Every once and a while you'll read a bad scroll...but you have to start somewhere. Once you've established which is the scroll of identify, it's up to you when to risk. The longer you collect scrolls, the better the chance a large stack is a stack of something bad. (Curse Armor) I tend to use identify scrolls on large stacks of like, 5 or more.