Do you want to go for your entire graduate career or just for a semester or two? That makes a huge difference in my opinion.
Are you still in undergrad? If you are, sometimes they will offer exchange programs to other countries so you'll possibly be with a few others from you school. If you're not, I went with a study abroad program not affiliated with my college, but I was completely by myself. I was introduced to the others in the group, which was sometimes nice even though I didn't live near them.
If you're considering going all alone and without a program, don't worry! People in Ireland will surprise you with how nice and friendly they are. I coped with it by joining clubs and making friends with my roommates/their friends. After they found out I wasn't a native, they would invite me out for drinks or ask if I needed help
I by nature am usually okay to wander off by myself, so with the friends I'd made from classes/clubs etc, I didn't have
too hard of a time being in Ireland for 6 months alone.
Hmmm less scary...well to be honest for the first week or so I was terrified. Landing in London Heathrow airport for an 8 hour layover made me realize I was literally all alone across the world from home. But after a week or so you settle in and get comfortable in your new city. I had my teddy bear (yes, I promise I'm 21 years old...), and being able to skype home was a life saver sometimes.
The experience of being abroad and the fabulous things you get to see make up for the moments that you're scared or homesick. Instead of letting myself feel homesick, I would plan a trip somewhere (traveling is SO much less expensive in Europe) and would get excited to travel rather than focusing on wanting to be home.
Annddd I just realized how long my response was! Sorry about that! haha