Crate training is probably the best way to housebreak a dog. You must use the dogs instinct to avoid soiling where it sleeps. Basically the crate is the dog's safe area, it's den more or less. From the beginning you toss a few toys, treats or whatever in the crate, let the dog get used to it being a safe, nice place, it's own room. You never ever use the crate for punishment.
If the dog is 18 weeks old (it's a week younger than my pup!) it should be able to hold its bowel & bladder for about 5 hours. Do not free feed the dog, scheduled meals are a must. My pup gets fed twice daily now, once at about 5:30 am, then again at 5:30pm. His last time out is 11pm, he either stays in the crate for the night, or for the last few weeks gets a treat by sleeping in our bed once in a while. He is a good little alarm clock, he's up & ready to go out by 5am.
You have to watch the pup like a hawk, watch the clock, taking the dog out on a regular basis. Praise that dog like they won the world series and the super bowl when they eliminate outdoors, give her a treat, keep something special like slices of roast beef on hand just for that. The dog soom learns that it can trade poop & pee for some really tasty treats, and will hold them for you, until you take it out.
As far as the jumping goes, you can see it coming. When the dog goes to jump on you, just turn away, walk away, and ignore the dog. The dog is trying to get attention, so when you give it the opposite, it quits trying to do that. Once it stops, again, time for a treat, and plenty of praise.
Once your dog gets a little better with the housebreaking, jumping, or whatever you are working on, treat every other, third, or fourth time, at varying intervals. Think like a slot machine; if you got the same coin back every time you put a coin in it would become boring quickly. You put in several dozen coins, one after another, in hopes of getting more than several dozen in return.
Dogs think very simple. They want good things to happen, and bad things to stop happening. If any of their behavior causes either of these to happen, they will repeat that behavior. If what they are doing makes good things stop, or bad things begin, they will eventually stop that behavior.
Look into clicker training. This pup is the first I've trained in 15 years, back then there wasn't much of any internet. It's kind of interesting that the terriers I've been training for over 30 years has been a sort of clicker training, without the clicker. Do a google search on clicker training, it really is a fun thing for the dog as well as the owner.
