I may not be a pro, but it seems that I have some advice to give. As far as CS goes, you should ALWAYS make it a priority over kills. I believe that about 10-sh cs = 1 kill, so last hitting an entire minion wave actually can give you more than enough gold. However, this works both ways. If both sides farm, neither gets more powerful. Getting kills is good. Great, even. Getting a lot of kills puts pressure on your lane, which can drawn the attention of the enemy team to your lane, and can relive pressure that would normally be on the carry from jungle ganks and roams from mid.
Though it is beneficial to get kills, it's not always possible. Just poking your opponent out of lane can get you a massive lead in CS, even if you don't get that extra gold. Keeping the minion wave in the middle of the lane, or pushed slightly towards your tower is also optimal, as you can cs, and don't have to worry as much about jungle ganks (since, as a jungler I can say there is nothing I like to see more than a lane that pushes at the wrong time). Freezing the wave, as many people call it, as well as last-hitting minions is something you have to practice. As a rule of thumb, you should have around 80-90 cs ad 10 minutes. This varies between roles, but that's optimal. Top lane usually gets less because they have melee range attacks, and are often not as strong in the AD department, so last hitting can be a little hard sometimes.
If you're having trouble with csing, I know it's tedious but go and make a custom game where it is only you and practice last hitting with no distractions, and try to get that 80+ cs at 10 minutes. Then try it on a bot game if you're still not confident or just go for it in unranked first to make sure you got it.
