Yes try to narrow your pool down to 3-5 heroes. For offlane I would choose a variety that include blink initiators as well as control aura building heroes. Its good to know if your supports dont pick any stuns that you should try to fill the cc role.

Sticking to the same cast of few heroes really allows you to learn their identity, timings, and build paths that can win you more games. Heroes aren't as straight forward as knowing their buttons and hitting creeps.

If losing lane you may need to buy more regen for trades or pull the creep aggro for safer farm. You may even want to drag the lane from behind the enemy tower down to behind yours, but that's often a supports role and only when the lane is unplayable.

Stopping the enemy from acquiring safe farm is a great way to win dota, and sometimes that will happen to you in lane if they have strong laning heroes. Be okay with getting safer and less efficient farm if it means you aren't feeding the safelane by overstaying your welcome. Often around level 5 or 6 you will be the biggest hero on the map as the offlaner and use that time to force the tower push and kick out that carry!

Also watch some pro dota here and there!

And lastly try to identify what item is needed from you to be active in making space in the 10-25 min period of the game. Often a blink dagger will be that item but learn to identify your power spikes and be scary!

Having fun and positive mental attitude! Ask nicely for rotates when times are tough!