Research your destination. Getting familiar with what to expect in terms of climate, culture and language will better prepare you and make the world of a difference in your travel experience! It's always a good idea to purchase a travel guide book for all your destinations; having it handy while you're travelling is a must!
Find out about medical facilities and ease-of-access to these most important 'landmarks' in all areas you'll be travelling in.
If you have special needs, such as a wheelchair or seeing-eye-dog, try to make prior arrangements well in advance to ensure you travel in safety and utmost comfort.
Last, but not least, purchase travel insurance with comprehensive coverage. If you have pre-existing illnesses, make sure your insurance covers those as well.