Instead of rolling it all into two arrows, expand voting into three categories:
Like | Quality | On-Topic
Dislike | Bad Quality | Off-Topic
The reasoning for this is that on other sites like Reddit and Voat, users tend to use the votes as an "I agree" or "I disagree" button, despite the efforts of the admins to convince them otherwise. This stems from too much ambiguity in what the votes represent - and with a tag voting system such as this, those ambiguities could be eliminated, causing people to be much more critical with their votes. Users would get one vote for each category - for example if there was a quality shitpost in /s/Jontron, I would put votes into
.>Like< | >Quality< | On-Topic
Dislike | Bad Quality | >Off-Topic<
(Even though we all know that any internet page associated with Jontron is automatically a shitpost sub) Perhaps a "shitpost" tag could be rolled into "Off-Topic" to further reduce voting ambiguities.
Said it before, say it again...
Make users post a relevant explanatory or challenging comment in order to vote. Set a highish minimum character count. Comment must be specifically relevant, so you can not just paste in ipsumlorumblabla.