What advice would you give others for helping to prevent soreness?

If you find out...let me know.  My dentist told me I had 'mouth ulcers' and to swish with arm salt water.  Well I do that and till have a white 'spot'? ulcer? on the bottom front of my lower teeth.  It is VERY painful and yes I've only had the bottom plate for 10 days now but I don't know what to do!  I dug some penicillan out of the cupboard and popped one of those..can't hurt and hopefully it will clear this up. 

I'm not far enough along on this odyssey to tell you if there is real merit in this or not.. but I'll share it anyway. The tech in my dentists office told me to wait until the stitches had dissolved, and then to chew bubble gum without my teeth in, daily. To toughen and encourage healing of the gums. I am dubious, but will try it, and offer it as an option. 

In the beginning couple of weeks I used a little oralgel to numb the sore spots.  Also have found that using sea-bond as the adhesive for the upper acts like a pad between my gums and the denture.

This sounds funny but it works. Whenever I have any gum soreness I buy a milkshake or eat ice cream which numbs the gum.