When hatching the egg make sure to have people with you. You can always solo but it's way easier with other people. Prepare for sleepless nights and constant worrying when you have to leave because these guys take 4 days to fully raise. You want to get as many imprints as possible which varies from taking them on a walk by whistle following and walking around, cuddling which just requires the simple button press of Triangle( I don't know Xbox or PC Controls) or hand feeding wyvern milk. Wait what wyvern milk, yes. There is a simple trap which can be found on YouTube. To make your life easier place a windmill( not a generator the break over time in scorched no reason to waste resources fixing it and supplying gas) right next to a stone pillar or a stone foundation with a wall on it, place a keypad so you can easily open and close the behemoth gate. Then simply find a femal wyvern and knock it out and grab the milk and go. Hope this helps and good luck.
I got a level 150 lightning egg and I was so excited to hatch the egg...that when I went to put the egg down I accidentally ate it instead. :( ps4 users: R2 ISN'T GONNA DROP THE EGG YOU'RE GONNA EAT IT LIKE ANY OTHER EGG. REMEMBER THIS. LOGIC BEFORE EXCITMENT.