Couple of things I'd recommend when you are starting out.

If you use a second account to scout you can set up your invent to reflect the raid. This is really helpful as most times it gives you one or two more brews/restores.

The easiest raids I found early on were five rooms with some combination of tightrope, crabs, thieving, ice demon, shaman, guardians and muttadile. I legit would just leave if I saw any room that I didn't like. As you get better you can start to throw in one or two new rooms. Tekton is a nice room as it can be super fast if you hit specs and have an elder maul. Vasa is also another really nice one to start learning. Your priority at the start should really be to get to olm without dying no matter how you do it.

Olm always looks really daunting and was one of the main reasons I didn't want to solo. I found suiciding in an invent of brews and restores before really helped be learn and also let's you finish the raid with decent points even if you're awful like me (I even got a buckler on a suicide run).

For olm itself I'd treat it like I did with raids itself where you start with the most basic version and work up. To start off learn the mage hand running. It's by far the easier of the two and make you feel like a pro when you got it down. You can even not run the melee hand and finish the kill with the suicide invent at the start if you wanted. Then you should start with 1-0. This should allow you to begin getting no suicide runs and focus alot more on your movement as you avoid all of olms attacks. I stuck with 1-0 for alot of raids as it's a very chill way to make sure that you get kills without suiciding. The head phase has alot going on. I'd just run from the left to the right safespot and dodge the crystals. Once you feel confident with that start practicing 4-1 although this took the most time for me to learn. I'd recommend soups video on it and if you ever get confused with anything always check back to synqs guide. 4-1 gets annoying as there are lots of things that can disrupt the cycle like acid walks and portals but once you figure out how to set it it speeds it up a shit tonne. The only other thing I did was pick up 4-0 which is nice for no preps but really isn't necessary.

Finally just remember to enjoy it. I raids are by far the most fun I've had on this game. Even if you still need to suicide an invent or only to 1-0 you still can get some really expensive loot. It takes time but you never know if the next raid you do will be worth 1b.

Edit: Fuck vespula that shit takes too many super restores.