The answer to this question depends on who you ask.

I will give you my opinion, but others may disagree. I will upvote my posts. I do not do it all the time, but I will do it.

There are people who believe you should never upvote your own post. But then there are people who upvote all of their posts.

I draw the line at upvoting my comments. I have on a rare occasion when I think that the comment needs to be seen by everyone. But this is very rare.

The benefit of upvote is that you guarantee that your posts receive some payout. The downside is if someone thinks you are being selfish and then Flags you.

If you upvote yourself you are preventing you ability to reward others. By upvoting and interacting with other people who develop a stronger sense of community (which in the long run is a better payout).

I hope this helps. Let me know if you have any more questions.