I have come across many people who have started learning a new language with me. Most of them had experience learning a new language before, but the experience of learning Hindi was different for them. I would not say learning Hindi is very difficult, but it will take some time for a person to understand the sentence structure. Because it's completely different from English. And if your Native language is English, then you have to practice how to twist your tongue within your mouth. Sometimes it's so funny. You should have a good ear to catch the new sound and copy the same.
I got few Hindi students who started learning it on their own, but after some time they just got stuck and couldn't improve.Yes, learning Hindi is not hard, but you have to give it some time. You have to be disciplined in your study, take time to understand the Hindi sentence structure and Hindi grammar, and most important you have to practice what you have learned with a person who can always correct you. You don't necessarily need a Hindi Tutor to start learning Hindi, but if you want to improve after learning basic Hindi words or after starting basic Hindi conversation ,you definitely need a Hindi teacher who would always be there to correct your mistakes and explain the difficult grammar rules to you.