Guides on jungling seem to change by season. Few I tried to watch on youtube were insufferable voices/jumping around. Looking more an explanation both on ultra basics as well as more concepts of why you do what. (It's mostly as simple as choosing red/blue/poison buff which I assume means killing them, but the way it's told and people talking about leashing sounds like more to it? I didnt think you could leash and stack pacs like in HON.) Seems very very rough if not getting a hand from team at start.
Without going into crazy detail, it's all about decision making, if you want a really good stream or set of VODs to watch, watch Nightblue3. He's was/is one of the highest ranked junglers in soloq and he usually has one of the top twitch streams. He's pretty good about explaining what he's doing most of the time.
In any case, on the technical things, the new Season 5 jungle is all about sustain. Panth has defense passives/procs that allow him to block damage. Nautilus has a shield. Rek'sai has a healing passive on his ability, etc. Typically you want to do two things when you start, 1) Start close to your bottom lane so you can get a 2 man leash or 2) Start Krugs (used to be golems) which are a pair of monsters Bot on blue side, top on red side. When you smite the Krug, you stun a monster every 6 autoattacks. This helps you sustain damage.
Your champ will help you develop your route next. High sustain champs can do a full clear, for example on the blue side: Krug > Red > Gromp > Blue > Wolves > Raptors > Maybe Krugs again. Not many champs can do a full clear. Some do partial clears, go back and get their updated machete and keep going. Some do three camps including two buffs and gank a lane.
You'll have to pay attention to the map to see, after your second buff, if you have an opportunity to gank a lane. If not keep farming. Feel free to make a custom game by yourself and just practice jungling. Get your speeds and routes down pat. The first clear usually makes or breaks your early game.
What I won't get into is invading/counter jungling champs like Nunu, Shaco, Lee Sin etc. These champs are very strong 1v1 levels 1-6 and can fuck up another junglers day by stealing their shit.
The only other tip outside experience or watching videos is this: Always gank/babysit the lanes that are ahead. If your bot lane is feeding and doing shitty, then don't waste your time with them. If your top lane is 3-0 keep ganking the lane, help them push the tower and let them start roaming and pushing other lanes. Always, always look to push an objective like a tower/dragon before going for a kill. You just have to know when the right time is to do that, and that will come with time.