Welcome to the fun my friend. Some tips.
Boomarang or the spear you can reclaim will be your friends as they are infinite, so try to get them as soon as possible, though just about all the projectiles are great. Though of course still try out all the items as you unlock them for whatever is the most fun to you.
Always hold down when you are falling. Always.
You have a period of invincibility after using magic, useful not just for fighting enemies, but also good if you need to survive past an area of spikes.
When you start to try and get faster times, note TNT will destroy normally non-destroyable blocks and you can drop down them as long as it leads to another floor.
Lightsword or whatever it's called is the best sword weapon, it will dissolve enemies, great against mushrooms.
Chickens are evil.