Your balance does not decrease, but your voting power does. You can see it here. It recharges by about 20% over 24 hours and as each full vote uses 2% you can make 10 full votes each day.

Given you do not have much HP you need to use your votes where they count. I suggest voting on 10 posts you like each day. There is a reward threshold (about 2.5c) under which it does not pay out, so it is probably not worth voting on comments that nobody else will vote. You will not earn too much from curation, but it builds over time if you keep powering up your rewards.

Another tip is do not use up all your good content before you build an audience as each post only earns for a week and duplicating them later may attract attention of some bots that look for copies. Duplication is generally discouraged.

Have fun with it.