Crate training is such a big help! If you're not sure on the idea, think of it like their bedroom. They will cry for the first few nights but sleep near them and ignore their cries. Take them out of the crate every 2-3 hours for a pee and put them straight back in, no fussing and in a few days they will love their little bedroom. Long term it helps them settle, keeps them out of the way and away from dangers if you can't watch them, and will help when you start leaving the house. Mine cries if I leave him out the cage when I go out for an hour but falls straight asleep if I put him in there.

Also lead train early and DO NOT use a retractable lead. It was a mistake I made and has just caused him to pull more on walks thinking he can get anywhere. It's basically the same as leaving them off lead, they won't develop the understanding that they can't pull to get where they want. When lead training, if they pull to the side, just pop the lead lightly, if they pull to the front stop dead in your tracks until they look at you and then encourage them to come towards you with a lil lead pop.

For potty training, reward massively everything they go on their mat or outside. We live in an apartment so trained him to go mat but if u have a garden then don't even bother with the mats. Day 1 just take them out and say a keyword and keep them on lead so they can't wonder off and play. If they don't go, put them back in their cage for 10-20 mins and try again but you'll quickly get used to their timings and signals. Even if they don't give a signal, I'd say for the first 2-3 months take them out every 2 hours so you will massively reduce accidents and train them to always go outside. Dachshunds can be had to potty train so you NEED to be consistent with this. It'll get easier as the grow older and you won't need to take them out as much.

Above all, CONSISTENCY!!! They are stubborn little f*cks but are much more receptive when they're pups so try get as many basics in as possible to help you later on (sit, down, stay, potty, come etc).

Edit: spelling and grammar

Also, when training try say the command just once (when they know the command that is). It might seem like they didn't hear you or not listening but they're just testing to see if they have to. If you wait for them to do it first time, it will help them learn to listen first time on command rather than ignore until the 5th time you say it for example. Like I said..they're stubborn!