My tips are:
-I like spicy eel much better than coffee because the speed boost lasts a really long time. You can get it from the trader for 1 ruby or as a serpent drop. And you can drink coffee in addition to get a double speed boost.
-Any time you get a break from being attacked, eat if your health is even a little low. You want to be as close to full health as possible when a bunch of flying serpents come at you. The times I've died have been when I didn't want to waste food so I waited to eat until I got lower. Sometimes you don't get a chance.
I take two types of food. My regular food is in the same row as my sword. It's something I have a lot of, like iridium salmon berries. If I have a break in between monsters, I eat from that.
Then I have my panic food, something with high health like cheese, cactus fruit, or life elixir. I have my sword in row 1/slot 1 and my panic food in row 2 and row 3, slot 1. That way if I'm in trouble I can do Tab Right-click. For me that's the fastest way to eat without having to think about it. I find that faster than moving the mouse wheel to get to slot 2 because it's easy to overshoot it in a panic, and clicking takes longer. The only downside to my strategy is that you have to finish eating to tab back to the sword, whereas if the food/sword are on the same row you can click on the sword while you're still swallowing and time is frozen.
-I've never worn a ruby ring but I second the iridium band. Best ring in the game imo because it combines everything you need leaving another slot open for something else. I like the crabshell ring in the other slot because it gives you +5 defense. You get it by killing all the crabs which is doable.
-I second the tip on bombs. I hardly ever use a pick axe in SC. Too slow. And keep in mind you can craft them on the fly if you've picked up iron and coal, which you usually do in SC. (or copper and coal for a cherry bomb.)
--Try to make sure you're holding your sword when you go down a ladder because sometimes a flying serpent comes at you right away with no warning.
-If I'm trying to reach level 100 for Qi, I'll drop a bomb or two right at the beginning around as many rocks as I can. If I don't get a ladder right away, I'll drop a staircase I have ready. I'll also drop a staircase on an infected floor because killing all those monsters takes too long.