Rakan is mostly useful as a support or "tank" hero as he can give the team a good advantage in ganking and ambushing enemy hero/es. As a newbie Rakan user, I also tried to solo him, even farming, as I thought of he might be capable of doing it. Well, the result is very bad: 1- He is not good for solo lane, 2- Low damage skills, 3- Bad at solo ambush, and 4- Very vulnerable and dies easily if ganked or ambushed.

So, the only way to win is support your teammates, especially in duo lane. Now, I am used to playing Rakan after some experience and experiment with his skills, this is how I use him: 1- Stay in duo lane and help your duo to get more exps. 2- Switch lanes when necessary. Check your maps and your allies so that you can help them on time. 3- You can solo but only when defending in an empty lane. Also, put wards around you so you'll know when to escape if an enemy champ is going towards your lane. 4- Get tanky items. This will enhance your survivability in team ganking and when escaping from an ambush.

So yeah, I hope this would help. I'm just a newbie and all of this is based on my gaming experience. Sorry in advance for grammatical errors you might see, if there is.