I’m concerned that I may be developing some bad habits with regard to how my mouth moves or tenses sometimes while I’m playing. This is the one area of the Beginner to Boss online course that I struggle with since Luke can’t actually see my technique and correct me. It seems that in order to achieve decent notes from certain holes (e.g. 2 draw, 8-10) I have to contort my mouth a bit, then when I move back to less challenging holes my mouth is not properly positioned for them. When I watch Luke playing, his face seems completely relaxed, and his mouth doesn’t appear to contort or strain in the way I feel mine is doing. Is this something beginners struggle with and will naturally improve over time or is this something that I should work to remedy now? Appreciate the feedback/advice. TIA.
I think its just practice. Muscle memory needs to develop quick responses. I only recently realised i get -2 without even thinking. Some bends start the same way first it seems you have to contort the inside of your mouth to get it but then you just do it on auto pilot one day. Just practice.
I just went through a bout of this. I watched a video on U Tube and the player said the following ,which helped me. Luke has a good u Tube post on this as well.
Place the harp in your mouth tilted slightly upward. The upper lip should fit into the low spot on the face plate and its basically along for the ride.
The harp should be back in your mouth but not enough to hit a tooth.
The lower lip is the should be placed over the bottom plate with the moist portion of the harp relaxed. The harp should hit the corner of your mouth to avoid air seeping in.
Before placing it form you lips like you are going to whistle. Relax and keep your tongue flat. Its the lower lip that you create a small hole with to isolate single notes.
I had to learn the hard way as I was not placing it far enough back and the low humidity caused the lips to dry and drag as I slid the harp to another note. Luke also has a U Tube post of this issue as well and I learned from I suggest you watch it. He did say to insert your finger behind your lower lip to make sure its relaxed.
I also hated the high draws and I suspect you are hitting them too hard as I was. The more you play like this the quicker you can break whatever habit causes you high end draws. I am friends with the right side of the harp now but do feel they will always be the notes that are a bit more difficult but practice tunes with numerous -8 and higher draws. This is what got me to the point they are not so tough. Keep a cup of water beside you. I am also a believer harps and humidity and chili whether as not friends. I put a second harp in a place that will keep it warm. On chili days the harp seems to be tougher to play. But this is only my opinion.
On your closing questions I fell the answers are yes and yes. Grooving a bad habit will slow your progress. Luke commented that you draw a high note about as hard as you would blow a lite candle without putting it out. This is about as good as one can get explaining how to play them.
One a final note when I use my lower lip to isolate a note and the harp is far enough in single notes get cleaner. Good practice cures about everything.
Hope what really helped me helps you.
Relaxation is key. The low notes are tricky and sound a bit off at first. Relaxing the breath will help. You want total relaxation of the face and neck when playing. Nothing on the harmonica requires force.
Same here, it’ll come with time.
I remember starting out and my lips and cheeks would be aching after practice, now it’s light as feather after an hour of playing.
it’s hard to “be relaxed” whilst also trying to something that is quite hard to do at first, but it gets easier.
@marcy0711 welcome to the forum! You’ve gotten lots of great replies here. Yes, the maxim is: try…and try again! And of course also: tension is the enemy of mastery.
We always too much force when we are first learning a new thing and then gradually we can relax into it more and more.
But “strive” for relaxation. 
Also, video yourself upload to YouTube (you can keep the link private if you want) and share the link here. I’m happy to give you feedback any time!
Rock on! 
I appreciate all the thoughtful responses and advice. I have completed the first three modules, but before I move on I think I’m going to go back to the beginning, really focus more on technique and staying relaxed. I love this instrument and I’m loving learning how to play it. I’m having so much fun. Thanks for a great course, Luke!
So smart! Can’t be too secure in the fundamentals. The value of developing the habit of relaxation cannot be overstated. Rock on!