When I called professionals to train my dog to be a service dog, they said I could save about $1000 by doing the basic obedience training myself, and teaching the dog 7 things. Except they weren't so basic. Again, I used a lot of YouTube videos from Zac George's Dog Training Revolution at this stage and started when Jesse was a puppy. That thousand-dollar savings was a motivator. :)
Foundational Commands Prior to Service Training
I was told to teach the following commands up-front to save that money. I did an okay job, and the professional trainer did the polishing, before the heavy training began.
1) Come and Sit in Front of Me
When you say "Fido, come," the dog immediately comes to you and sits in front of you, watching you, until you release it. Most trainers teach dogs to "come" by using a long leash and rewards for coming. Every time Jesse comes to me, I reward her verbally, even to this day, to encourage her to always listen, to follow even off-leash, and come back in the middle of an off-leash beach outing.
2) Sit, Down, Stay Until Released
When you say "Fido, sit" or "down" or "stay," the dog does so and watches until you release it. These are easy commands to teach using treats and YouTube videos.
3) Heel (on a slack leash with no pulling)
Fido walks on your left side (if you are right-handed and able to use your hands). The dog does not anxiously move ahead, pull on the leash, or gawk around. Fido sits when you stop and resumes walking when you walk. The dog gradually learns to do this automatically, without voice commands. You'll find many techniques on YouTube for teaching the "Heel" command, but I needed some trainer help to polish this.
When you say, "Fido, place," the dog goes to a designated spot (usually a doggie bed) and lies quietly until released. This is actually one of the easiest training tasks (refer to YouTube for techniques).
5) Leave It
When you say, "Fido, leave it," the dog drops whatever it has in its mouth--or doesn't pick it up to begin with.
When you say "All Done," the dog knows training time is over--I was told to avoid the word "okay" as a release word because we say that word a lot in conversation. I personally use the word "Okay" to release her to interact with others periodically (again, my trainer would frown on this and it probably stresses the dog).
Remember: Each time you take your dog into a new environment (e.g., from home to yard or yard to park), you have to re-teach the skill.