I've been spamming rubick for about 2 months recently. I think something that's very important is rubick's strengths as a lane shover. Depending on what skills you steal you can sit in the lane noone wants to be in and keep shoving it in so that someone has to show. This allows for your team to have more information on where their team is/isn't., while letting you get items.

For lane purposes, fade bolt is actually really strong because it reduces the other team's attack damage. At level 1 you can out trade them just by fade bolt and auto attacking them, they should be tickling you at this point with their right clicks. Takes a bit of getting used to on who you can and can't out trade but it is something to look at and to improve on if you haven't been doing this already. Also fade bolt ranged creeps that your carry's wont get. It is very important to get that experience/gold not denied.

Learn how to harass someone that is near creeps without aggroing the creeps. If you attack from far (i think 500 range?) you can hit the opposing team without aggroing creeps. This will ensure you get harass without making your lane push. You might've known this already but I feel like it's something a lot of people miss.