A big requirement to play Mid Lane is to roam to help the other lanes, always look for easy to gank champions that dont have alot of CC & Escapes, Warding is key aswell so i recommend buying Control Ward every back.
Mid is the easiest lane to gank (In general) so you have to be more careful with vision and wave management. I recommend watching a couple youtube videos for tips
first of all,you need to think about what is your adc style,if you are a ez, varus player you must like skill shot mages like xerath , vel koz.you can think about corki that is similar to adc except for what to against mages and assassins.late games champs like azir , ryze and anivia would be a good option to you too.
Here is a list of champions in general.
Reason why I link this is because I find it easier to list champions by type rather then by name as that makes it much easier.
Just press ctrl+F and then type in the champion type to quickly scroll trough the list of that type of champion.
If you look trough the list and know what is actually played mid you'll find that mainly; Burst (Ahri), Assasin (Katarina) Battlemage (Viktor) and Artillery (Xerath) champions are played there.
So, just look at the list, check which of these types of champions that you like and start trying them out.
As with anything its smarter to start with the easier marked champions and work your way up, but alot also comes down to knowing what the opponent can do.
So changing lanes also means learning your matchups.
I dont know if this is what your looking for but it should atleast help filter trough your options more easy.
Play as a ranged midlaner, and try to play as you would do as an ADC, but rely less on your AA and more on your abilities. Instead of making AD items build AP. Soon enough you will get used to it as it's not too different from botlane, only thing is that you cannot rely on your support anymore.
Here is a list of champions in general.
Reason why I link this is because I find it easier to list champions by type rather then by name as that makes it much easier.
Just press ctrl+F and then type in the champion type to quickly scroll trough the list of that type of champion.
If you look trough the list and know what is actually played mid you'll find that mainly; Burst (Ahri), Assasin (Katarina) Battlemage (Viktor) and Artillery (Xerath) champions are played there.
So, just look at the list, check which of these types of champions that you like and start trying them out.
As with anything its smarter to start with the easier marked champions and work your way up, but alot also comes down to knowing what the opponent can do.
So changing lanes also means learning your matchups.
I dont know if this is what your looking for but it should atleast help filter trough your options more easy.