I can throw a few tips your way.
You NEED FLAT Armor seals. For a lot of champions it's the difference in dying to red buff or not. Tankier champs can get by with scaling runes, but for a general rule of thumb, run flat armor seals.
Go into a Custom match before jungling with a new champion to figure out your route.
Playing a tankier champ? Start Gromp, blue, then Red buff. If you're healthy, gank, if not, back.
Playing an assassin or dps champ or something? Start Krugs, Red, then blue buff.
Of course, this is very general. If you're playing a more sturdier jungler you can start based on where you want to gank first, like if you plan on ganking top lane start on the bottom camps and work upwards.
SCUTTLER CRAB! You want almost 100 gold and a nice chunk of xp? A free ward for important objectives and roaming routes? Movement speed buff? Free sustain? Surely such a prize must cost some serious effort! ... No. Walk into river and punch that adorable crab. A lot of the time the poor thing gets stuck on a wall and you don't even gotta chase it around. You and the enemy jungler should be contesting these cute little buddies, they're OP as Release Xin.
Don't gank a lane just because they're behind or they're ahead or they're the carry or WHATEVER. While you're getting comfortable, gank the lane that you know you can accomplish something in. Yeah, you WANT to shut that Katarina down before she gets out of control, but that doesn't mean you have to turret dive. Run at her menacingly a few times early on, maybe force her flash, and she'll play more passive while you go bot lane and get your ADC fed. This doesn't apply to higher MMRs but just being a threat can be enough to win a lane for somebody. Kind of a Blitzcrank mentality you could say. Zone by letting the enemy know you exist.
You're the jungler, you have more control over the flow of the mid game than anybody else from a mechanical standpoint. Apply pressure in lanes and pay attention to the enemy jungler. You see him top lane? Tell bot lane to push the lane and go to dragon because that's a free dragon. Of course, considering your level, it could be difficult getting your team to follow. In that case, worry less about dragons unless you can safely solo it and more about turrets and lanes.
For general rules of thumb, that's all I got really. If you're having trouble with jungle routes I can show you in game some time if you want though. I'm not diamond or anything fancy but I'd be happy to help.
