I almost always fly solo, so I am quite accustomed to this. I have done long haul (10.5 hours DFW-GRU) in economy. I paid the upgrade fee on the way back! If you are able to sleep, it helps. I take medicine as soon as wheels are up sometimes (do wait to take off shoes and take meds, just in case you have to get off due to weather/mechanics. Emirates is a good choice for long haul economy (I always suggest uprgrading if you can; I am unfamiliar with Emirates' policies). I cannot handle the long haul economy now (my back), but the trick to all of it is making the environment comfortable for you.

Download music or TV you like on a device that does not require internet--just in case. Bring a book, a magazine, etc. I like to watch TV in bed at night (I would download thrillers and mysteries--the things you become engrossed in but are not so serious you think too hard). Then I slip my headphones in, lean to the side with a good pillow and blanket (Emirates probably provides this--here in the States, you bring your own for US carriers sometimes).

I prefer windows when I need to rest because you can lean into it with a pillow. Aisles, not so much, plus people always walking by, etc. Your seatmates know you will need to get up for the toilet at some point. I try to time this when the middle or aisle gets up if I can, so as to cause less disturbance. Drink (but not alcohol if you don't know how it affects you in the air). Keep hydrated. Long haul can dry you out. I avoid any spicy foods on long flights. Who wants heartburn at 40K!

You will find myriad travel articles and tips (likely too many), but the key is to plan for as much as you can to do. Dress very comfortably or bring something like track/sweatpants and a large t-shirt Being comfortable is a must. It also helps when you can change before landing. T that end, baby wipes can help you feel more alive if you don't have lounge access.

Prepare for what you need.
Always be respectful to other passengers who are also trying to survive hours in the back of the plane.
Sleep as much of it as possible!

Enjoy!