Suggestions for Travel Credit Cards

Good afternoon!  I am new to the biggerpockets community and excited to be a sponge.  My wife and I are working on saving money to buy properties.  In the meantime, we want to take advantage of building points on credit cards for traveling.  What are your recommendations?  We want to accumulate as many air miles and hotel points as possible.  What are your experiences that we can learn from?  Thank you in advance for your input!