You need to have rules for either possibility. For example, lets assume market moved up and you get an order to go long, and assume you know where you want to put your stop.
Now right after you get in the trade, market goes down, and say you have 2 contracts.
At this point, I am going to discuss and actual trade. So market is now going against you and you see a bunch of red candles. So what I did was set 1 contract target to get me out at BE since I decided this was no longer a good trade, kept my original stop, and set 1 contract for a small profit target that was just below the current recent high.
Why did I no longer like the trade:
a) I did not get in at a good price to begin with
b) I did not wait for a confirmation from my indicator.
c) I went in with more contracts than I should have for a weak setup.
However, what I could also do was get in at a better price if the market took out 1 of my contracts at BE, if I don't move my stop.
So market did get 1 contract out at BE, and then started to go down again. but not enough to give me room to average down. I was also now thinking about killing this trade entirely for a small loss, but decided I am now in the trade, and no longer thinking non emotionally. Once you are in a trade, you are less likely to think correctly than when you got in the trade before money was at risk, so the best thing to do is to honor your targets and stops. Also, you need to be willingly to mentally accept that your trade is going to be a loser before you take the trade.
So at this point, I decided to leave both target and stop alone, and price eventually hit my target, and of course went even higher, so I should in fact have either averaged up or gotten back into this trade at a higher price.
I eventually did go in once more at even a higher price and again got out with a small profit since we were at the highs of the day, but again this was not a great decision since the market went higher and broke those highs.
So, I think you can average in once if you either reduce size and/or planned to do this before your original stop is hit. Also, you can either average up or buy at a higher price if you get another valid signal, and you need to not be afraid when trading with real money.