As for actual freeze drying, I recommend not overloading the trays. Do not mix frozen food with room temperature non-frozen food as some of it will be inconsistent.
Another tip, you can freeze dry anything. Frozen chicken livers made excellent treats for my dogs. You can freeze dry raw meat and stick it in a mylar bag and it will be shelf stable. Pretty crazy.
Happy to answer any specific questions.
As I don't have one, I can't answer in specifics. However I can give the answer I give to all hobbiests;
If you can afford it, and you'll get pleasure from experimenting, then go for it. The worst you'll discover is that it's not for you. More likely you'll learn something new and interesting.
Then vacuum seal the bags and put them in the freezer.
Room temperature dehydration might be easier and give results as good or better. Have you tried commercial freeze dried blueberries? Is there something special about the texture or flavor that you find superior enough to invest in achieving?
If you don't know why did you comment?
ive had freeze dried fruits and didn't care for the results, compared to regular "dehydrated". but others might prefer things that way; perhaps its especially good for blueberries. i think it makes apples into packing peanuts.
Freeze drying does give you a new way to get fruit flavors in food, so experiment.