How can I get better at IV insertion on dehydrated patients?

Have the patient dangle the arm for a minute or so and also try applying a warm compress to bring the veins to the surface more easily. I’ve used a 22 gauge butterfly for brief infusions in the past.

Sometimes a smaller gauge needle, may need to use a non traditional site( foot example) and maybe try without a tourniquet. Some things I learned ☺️
Sometimes there are no options but a central line etc

Practice practice, learn where your valves are and practice. Educate where they should be. Follow an old school nurse during IVs.