https://pixeldungeon.fandom.com/wiki/Shattered_Pixel_Dungeon is a great resource if you are new to the game and genre, although I suggest first trying discovering everything by yourself (prepare to die a lot) and start reading the wiki after getting through the first boss on lvl 5.
I've been playing SPD for years now and for me the best strategy to win the game is to keep Scrolls of Upgrade until you get a hold of a weapon of at least tier 4, same goes for armor. This makes the initial levels much more risky, but if you survive it's a matter of not making mistakes or getting yourself into high risk situations. Using this method I get to the Amulet in about 30% of the runs. Since the recent updates getting back to the ground has become a much more fun challenge.
Besides postponing the use of Scrolls of Upgrade, here are a few things that work for me:
* You don't have to identify potions and scrolls right away, often you can keep them until you gather more information. For example, killed flies sometimes drop health potion and they are on early levels, so you can learn the color without using it.
* Before you get the Scroll Holder that protects the scrolls from fire, it's a good idea to stash all the scrolls in water at the beginning of each level and retrieve them back before going to the next one.
* Scrolls of Mapping are absolutely crucial on levels >20 because of the traps and they are relatively cheap in the first two shops.
* Summoning trap rooms are great to gather a lot of xp if you have potions of paralytic gas and fire/toxic gas. After the level is cleared, you just open the doors by throwing something at it, go as far away as possible, throw paralytic and then fire/toxic potions. And run to the next level.