I need help on both of these tricks.
When I am trying to attempt boingy boing, the yoyo starts to go sideways or it comes out of the gap that it’s supposed to bounce between.
When I try to eli hop, the yoyo swings around my finger instead of shoot up.
What am I doing wrong?
Can’t really help you with boingy boing because I am still hopelessly stuck on that but I can help with the eli hops. I think what’s happening is that you’re hopping with a bit too much force and/or not bringin your hands together quickly enough to give the string enough slack to actually hop. Try slowing down a little bit and starting with a bit more slack so that the trapeze you start from has a bit more of a dip in it.
Yuki
In relation to how long I’ve been yoyoing (all of 5+ months), these two tricks easily took the longest for me to learn. I would suggest skipping them for now. Get more acquainted with the yoyo, the string, your throw… Come back to the tricks in two or three weeks, and go after them with decisiveness.
I agree. Skip them and come back. If you focus on just these two tricks you wont progress at all in other aspects of yoyoing.
Funny, I was gonna say, “attack them with the decisiveness of a samurai.” 
For boingy boing line up the strings so the yoyo doesn’t come out.
For eli hops watch the man on the flying trapeze video where andre shows you how to shoot it up. Just do the same thing, but instead of catching it land it on the string.
Well, if you’re asking about these two tricks than i can help you with my friend.
For starter : Boing-e-Boing
-Keep your throwhand directly above the non throwhand and the strings ABSOLUTELY need to be DEAD CENTER of the yoyo that way, when you bounce it with your throwhand the yoyo won’t go sideway ot bounces out , it took me 1 months to get familiar with the boing-e-boing . Try to keep the yoyo straight and don’t let it touches the side .
Next : Eli hops
-when you first starts, i would suggest keeping the string shorten alil bit that way the yoyo will land more accurate and start with a small tiny forces ,just enough to bring the yoyo up 3-4 inches away from your hand and then quickly move your non-throw hand back and forth . Keeping the yoyo straight does help you alot and try to curl your non throw hand pointer just enough to make a hook so that the yoyo won’t fall out your hands .
Hope this helps !
Looks like you’ve already got some good advice, hope you don’t mind if I give you a little more. Boing-E Boing begins with the split bottom mount, I’m sure you’re familiar with it since your practicing the trick. My advice is try to boing the moment you’re leaving the split bottom mount. Don’t let your yo yo just sit in the middle of the strings spinning. Its going to be a lot harder for you to get decent boings if you try boinging from a yo yo that you’re just holding there. You loose a lot of valuable momentum. Keep the entire trick as smooth as possible. It also helps me if I exagerate the hand motions a little. Find a good speed and keep a rhythm to it. You’ll get it in no time! 
For Eli hops it just requires practice what I try to do to is to do small hops and get gradually bigger and bigger so they get more constant hitting the string
Boingy boing: I dunno if it’s considered cheating, but in addition to boinging right from the mount, I also move my throw hand index finger directionally just one time before swapping to the expected up and down motion.
Also… Can do it with certain yoyos more easily. Can’t do it with Lyn Fury at all. DM2 relatively consistently.
I am definitely a beginner also, bit didn’t wait months.
Eli hops on the other hand… Je suck grand-temps
Boingy boing seems to be one of those tricks that takes a short time to learn, but a lifetime to master…so to speak, anyway.
I’ve thought I “had it” numerous times only to figure out that I didn’t have it down pat.
But now I think I have it. The trick for me is to leave your throw hand wrist completely limp, and do the boing-ing with your forearm, elbow, and bicep. When I used my wrist instead, which is the first thing you try, I was always getting ahead of the timing and there wasn’t enough slack in the motion for the yoyo to really go as far as possible in both directions. With the wrist limp though, makes all the difference for me.
for boingy boing every time it tilts just line it up, when your going to start the motion start out slowly then go a little faster and go with the flow all you need is momentum
Thanks for the tips everyone. I am getting the hang of boingy boing. I can do it about 4 or 5 times before it comes out of the strings. It’s much better than me getting only the very first bounce. As for eli hops, I am practicing to get the hop straight. When I hop, it goes pretty far, but sometimes I can catch it. I will practice both of these more until I can do them perfectly.
For Eli hops to keep the yoyo straight ( my way ) shoot the yoyo far from your :
If your right handed shoot to the right , left handed shoot to the left . I found out that if you shoot it that way then when you catch it the yoyo won’t tilt or lean to the side , it helps me to get to 5-6 hops every times ^^
i did that. forgot boing e boing exsisted for like 2 months. i decide to try again. got it after 3 trys! youll never know, you pick up tricks on the way! had trouble with eli hops too! not as much as i did with boing r boing though -_-
For EliHops:
Pretend to clap your hands. This is how I learned. You know what? Actually clap your hands together while hopping the yoyo.
I figured this trick out on my own, but watching someone actually use the trick really helped. Try to really pop the yoyo onto the front string instead of threading the string through the yoyo. Also try to keep the strings that the yoyo is landing on taut. It is really hard to land on a string with slack.