One of my best tips for you is to insist on going to the breeders home to see the puppies. Often times, the "breeder" will insist on meeting you at "X" place so that you don't have to drive "X" amount of miles and even if you say you live close, will still ask if they can meet you in the middle. This, to me, has always been a bad sign and will always make me run. A breeder that doesn't want you to see where s/he breeds their dogs usually has something to hide. A reputable breeder is generally more than willing to let you come over, interact with the puppies, maybe meet the mother, etc. (Though, it should be noted, even some millers and BYBers will allow you to come over. These ones are usually good at making everything look "presentable" and/or feel they have nothing to hide, anyway)

Likewise, don't be afraid to ask questions! A good breeder won't mind answering and will actually appreciate that you're trying to seek as much knowledge about the breed as possible. Any question you have, ask it. If they refuse to answer and/or don't seem to know the answer... run.

Ask if there is a contract (a reputable breeder will always say yes, a hobby breeder will almost always say yes, and a miller/BYB may or may not say yes) and ask if you can read it. Read it carefully. If it says that the breeder will take the dog back if you ever decide you can't have him/her any more during his entire life, that's good. However, most not-so reputable breeders will pull a "first few months of life" or "first year" because it looks good. But I cannot begin to tell you how many of their dogs end up in the shelter because they refuse to take them back after the cut off date. Read that contract carefully, though, so you know what you're agreeing to.

Good breeders will usually only breed one or two breeds (two is not uncommon, more than is pushing it), breeds because they love the breed not to make a quick dollar, will never produce more than one litter a year (it's not uncommon for them to go years without breeding a litter), will be more than willing to share the good and the bad and won't candy coat the breed just to quickly sell the puppies, will sell all pet quality dogs under a spay/neuter contract, and often times will participate in some kind of events. (Not always conformation shows - though, I'm not sure what Scottish Terriers could participate in...)

It can be a bit overwhelming finding a good breeder. Breed rescues may be something you want to consider. There are so many poodles breed these days (and poodle mixes) that I'm sure there are a plethora of Poodle rescues out there. Scottish Terriers, though... that, I'm not so sure of.