There are no hard and fast rules here. You could seek friends' recommendations, or you could visit a few boarding kennels yourself and have a talk with the people running them. See if you feel comfortable with them and observe the way they treat the animals. When you are there, check the kennels and ask if they have an attending vet to see to your pet should he/she fall sick during their stay. Ask if they require all animals to be vaccinated as a boarding requirement.
If you do not feel comfortable sending your pet to a boarding kennel, you may wish to find a pet sitter whom you trust. Pet sitters usually visit your place once a day to keep your pet company, do general tidying up and feeding. You could also enlist the help of your family members or friends to help feed, clean, exercise and keep your pet happy while you’re away.
Don’t ever base your decision on the price that a boarding kennel charges - an expensive kennel does not ensure a better kennel. The safest way is to trust your instincts - whatever feels right (after doing your research) probably is.