I'm sure there's someone out there who has it down to a science, but here's my experience.
Have wards on Baron and Dragon at all times if possible, if a team member is forgetting to buy pink wards ask if they can pop one in the back on the pit. That way it's not visible to the enemy at first assuming they don't look for it. That way you have control and that ward they weren't buying is put to use.
Buffs, important. After my first clear I generally give the mid blue and try to get my adc or top red depending on who their champ is. As a jungler I'd rather have that buff doing work on a laner than "wasted" on myself.
NOTE: if you need the buffs for your clear don't be afraid to take them. Like if you're mana intensive. Also don't give the buff to your teammate if they are feeding. It's a hard decision, but if they're going to give it over in the short time it's active it's not worth it.
Ganking and clearing are dependent. Are you a hard 6 ganker like
? Clear until 6 and tell your laners this. Are you a champ who can gank early like
? Ping and let your laners know you're looking for an early gank. If everything is pushed just farm. Are you bot and your adc and supp are pushed to the enemy turret? Pop a ward in the brush or take scuttle. If you're strong enough, solo drag after planting some vision.
Are you top and your laner is pushed to the enemy turret? Ask if they want to dive them or counter jg in that area so if you get caught your top is there to help.
It's a popular belief that you surrender a losing/feeding lane. I don't agree with this philosophy. If you can shut down that player in a 2v1 or have your mid roam up for a 3v1, shut them down. They will only get stronger if you ignore them while your already behind laner gets more behind.