Your best potty training aid is your puppys' crate. Anytime that someone is unable to be watching/spending time with the puppy, use a crate. Similar to how one would use a playpen for a baby or toddler....even if he will only be alone for what might be a few minutes, use the crate or take puppy with you. 

Make crate training a POSITIVE experience, it is NOT a punishment at all, in fact..the den is an important place for wild dogs, and is often their place of 'safety'. The same thing applies to the "crate", it is your puppys' den/safe place. 

Place the puppy in the crate while you are home as well as when you are going to be gone for a few hours, but remember a young puppy can only holds its bladder for a short time, especially a small breed puppy.   Start the puppy out slowly, placing him in the crate for just 15 minutes or so at first, in the same room as you are going to be.  Chances are good that the pup will make a fuss/whine/bark, etc...at first, but it is extremely important that you NOT LET THE PUPPY out of his crate, simply because he is complaining (THIS will only teach the puppy that crying = someone coming to get him (o:)  When you bring the puppy out of his crate, make sure it is at a time when he is peaceful, and always take him out to go potty immediately.

By crating when you are home AND while you are gone, the puppy becomes comfortable in the crate and not worried that you will not return, or that you are leaving him/her alone. This helps to eliminate separation anxiety later in life. 

Most puppies will not soil their "den", UNLESS they have no other option and simply cannot hold it any longer.  The first couple of tries you might have some accidents, but don't be discouraged.  Here are some tips to help avoid accidents during the night for the first few weeks is by following this routine: 

1. set your alarm for about 3 hrs after your normal bed time. When the alarm goes off, get up immediately, go to the crate and CARRY the pup outside. Place him on the ground and encourage him to eliminate. PRAISE when he does, and bring him back to the crate. Go back to bed. 
Get up again, in another 3-4 hours and take puppy outside again, PRAISE him for going potty...and again, put him back in his crate...unless  of course it is time for you to get up as well (o:

2. After about a week or so, if the pup has done well, and not messed in his crate during the nite...then you can try getting up just once during the nite.  When you get up in the morning...FIRST THING, TAKE the puppy outside to 'go potty' BEFORE you do anything else.  I like to use a verbal command, and tell the puppy "outside" or "go potty" and don't forget to PRAISE PRAISE PRAISE, tell the puppy what a good boy or good girl he/she is...you can say 'good potty' also....TRUST ME, they will learn to understand exactly what it is you are asking them to do, and will understand the 'goodness' of what they have done...Consistency is the KEY.  
Bring the puppy back in the house, give him breakfast...and remember, within 10-30 minutes after the puppy 'eats', it will have to have bowel movement..so back outside once more after he eats breakfast to 'go potty'.  If you have time to play with the puppy, now is a good time, after his nite in the crate...Remember to let him out to go potty once more before putting him back in his crate...or keep him with you and watch him closely.  Pups seem to have to 'go potty' most often after waking up, after playing and after they are done eating...Seems like all the time doesn't it?  As the puppy grows, potty times will be less frequent, so just have patience.  

3. Repeat the same as above, for lunch and early evening feedings...Be consistent and develop a pattern with your puppy...You will be amazed at how quick he catches on!

It is also important that the puppys' crate is NOT TOO BIG, as if it is, he will potty on one end, and sleep on the other...The pups crate should not be MUCH bigger than that will allow him to stand up, turn around, stretch out comfortably.

Also, everytime you put the puppy in the 'crate', be sure to tell him "kennel"....as he grows, he will learn that when you tell him its time to go in the kennel...he will run in on his own to snuggle into his bed.  There will be times, if his kennel is left open...that he will wander in on his own..just to take a nap.

In conjunction with crate training, potty training starts immediately. 

Whenever you remove the puppy from the crate or just want the puppy to "go potty," take the dog to the door that will always be used to "go outside." Use the SAME door throughout the training period. 

Reminder: During housebreaking DO NOT allow the pup outside to eliminate alone or loose in the yard. Yes, that means in the rain, snow, whatever: YOU GO OUTSIDE ALSO. Give the puppy plenty of time. Don't rush or you will be sorry.  When the puppy urinates or defecates, praise the puppy with "Good Potty" and even offer a tiny treat (my personal favorite 'treat' when training a puppy is to cut up very tiny pieces of hotdog...you never want a treat/reward to be so big that the puppy has to spend more than a couple seconds consuming it...a 'quick' reward is always the best, to better keep him focused) 

Continue to wait. When the puppy poops, again praise the puppy with "Good Potty" and give a treat.  If the puppy does not "potty" even after staying outside 15 minutes, return back inside, place the puppy back into the crate or keep him with you, wait 15 minutes and start again from the beginning. 

If done religiously, this training process should take only about 2 weeks for the puppy to understand. This method will work with any dog, regardless of age. If you adopt a dog from a shelter or a rescue program, follow the same routine.  Remember, even though the dog is older or even an adult, he still does not know the rules of your home, and may not have ever BEEN in a house. Be PATIENT and this method WILL work. 

Take it slow and easy...be CONSISTENT and  PATIENT....and have FUN with your dog!