So I just moved in here, I'm thinking about getting a dog for my new apt. I noticed some tenants have BIG dogs, goodness! But I want a small-medium dog. How do u train a dog in an apartment? I was thinking of when I leave for work, I put him in a cage/crate, then let him out & walk him when I return. Any advice? This apt doesn't allow aggressive breeds. How to train? Thanks!

Initially you will appreciate that the crate gives your dog a safe place to relax (and gives you a break). In the future it will be a great benefit that your dog has been crate trained if he needs surgery or will travel. Most likely, your dog will like the crate if you are careful not push him too quickly. Place the crate with a comfy blanket inside nearby where you will be relaxing for awhile and set a trail of treats leading into the back of the crate. Allow your dog in the room and leave the crate door open while you relax. Eventually (or in a few seconds) your dog will get the treats and explore the crate. When you see him go in the crate, get up and put a few more treats in the back of the crate. Repeat this a few times until he is unhesitatingly going in for the treats and not rushing to escape the crate. Say "kennel" and take your dog gently by the collar and toss a treat in the crate. Most likely he will follow the treat into the crate. Gently block him from leaving the crate with your body and feed him treats in a steady stream. Once he relaxes and lays down, continue to do feed, but space out the treats a few seconds apart. Slow your treats down to about every 10 seconds when he seems especially calm. Let him out of the crate when he is nice and calm and take a break from training. Repeat the previous step, but this time instead of blocking with your body, close the door to the crate. Prepare a yummy chew toy (by filling a toy with cream cheese for example). Say "kennel" just before grasping your dog's collar and walking him into the crate. Once he is in the crate, give him the chewy and close the door. Once he is engrossed in chewing, get up and walk around, occasionally going out of sight. Release him from the crate before he finishes chewing (or before he wakes up from dosing off) and only if he is calm. If your dog should fuss in the crate you must ignore it (unless he seems truly hurt) and release him only when he is calm, otherwise he will learn to fuss in order to be released.

Good tips on crate training. I would think that the 'how' of training would be the same in an apartment or a house, with the exception of when you take them outside, you have to go with them vs. opening the back door and letting them run in the back yard.

I would agree that the breed you get is a very important. In an apartment you would want a dog that is quiet, doesn't chew (like on walls or cabinets, since they aren't yours and could cause trouble with landlord), doesn't need a lot of exercise (sure all dogs need exercise but some require more and more aggressive exercise) and friendly.