Looking for coaching.

Hello i am a silver top lane main (riven). i don't play ranked often as i really only know how to play riven and there's too many champs that can make her irrelevant (alistar, lucian, ezreal, tristana, lulu, and others) not to mention the several top lane matchups that can be extremely difficult. i need to expand my champion pool. I can pay for coaching but a lot of times i am tight on money due to bills. would love to hear from someone who can help me to find a couple champions to match my play style and that can point out what i can do to improve.