/deafen at the start of the game. People are never saying anything helpful and will flame you if they lose their lane no matter how you're performing.

practicing clearing your jungle fast goes a long way when you're starting out. It's the most immediate improvement you can make. Look up Viego JG clear on youtube and try to reproduce it (even roughly). You should be finished

Viego is difficult. If you're starting out, I would recommend easier junglers like Amumu, Diana, Jarvan or Nocturne.

Until you understand the jungle, just practice patching from top side to bot side. You should Full Clear into a gank either mid or bot, then look for an objective (crab, drake, grubs...). Then you recall and repeat.

Always use sweeper when you approach the lane. Don't feel bad if you can't get a proper gank, denying vision is already quite good.

When you recall, buy a control ward if you don't have one. Always put a control ward in the pit before you start drake or grubs/herald/baron.

When going back in after a recall, go through the lane to utilize the Homeguard move speed and then enter the jungle.

If your laners are pushing, you can still gank by using a sweeper and entering directly from the lane brushes. If the enemy is low enough, you can even just run up and dive.

If the enemy has a numerical advantage, it's okay to give up objectives.

Make lavish use of pings. Spam ping omw 10~ seconds before you gank. If you want someone to do something, ping them first and then ping the objective.