When doing any sort of magick, It has been said to keep in mind that the subconscious mind does not understand NOT.
So when you wish to manifest what you want, you don’t want to focus on what NOT to happen.
In saying this when people do evocations they sometimes tell the spirit “and harm none.”
If I wish to do sigil magick to bring myself some money and make sure no one is harmed what is the best way to go about that?
“Harm none” is a positive statement - it’s like setting a value of a thing to zero on a computer.
Imagine you have to fill in a field on an application form, like when you register for a forum and you HAVE to put in a username, or an online order where you MUST give them your postcode/zip - if you don’t, you can’t hit submit on the form, so in this case, in the hypothetical field of “Number of people it’s okay to harm” you put 0.
That’s the way I see it anyway, other people might have better insights. 
'Newton’s third law is: For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects"
I don’t think ‘Harm None’ is even realistic, based on the above scientific and natural principles. Everything received in a positive form in the material realm, draws or takes energy away from another. As a Black Magick user, I just have to realize my actions have consequences and I have to be prepared to accept them, good or bad, taking full ownership. ‘Harm None’ seem like a cop-out, akin to the Witches Reed.
Not necessarily, when it’s trade - Wallace Wattles covers this in his book, the Sceince Of Getting Rich.
For example, I bought myself a really posh leather planner last week to use for 2017, it cost me money, yes, but it was a planned-for expense and the use value and enjoyment I’ll get from it will be more than I would have had from possessing the money, which is primarily a medium of exchanging energy.
We exchange energy when we talk to a friend, make love, raise a child, walk a dog - none of these should be zero sum kinds of experiences, in fact we think it’s pathological when they are!
So why should money be any different?
IMHO, when you put out the intention for money (since that’s the example being used here), there are many channels it could come through. Some of those channels could potentially be harmful to someone, in some way. For instance,a relative suddenly dies, leaving you money. Or it could happen to you. An accident in which you receive a settlement, etc. OTOH, it can come from a source that doesn’t hurt anyone. A good night at the casino, a lottery win, or even money coming back to you in the form of a refund for an over payment. Some might say winning money at the casino or from the lottery is taking money from someone, but no. The money was spent on lottery tickets, or at the casino, freely and willingly. If it was money they shouldn’t have spent, that’s on them, not you.
The point being, by saying “and it harms none”, is simply telling the multiverse to use a channel that brings it to you without harming anyone, or taking from anyone. I don’t see it as a cop out, simply as an ethical choice you are free to make, or not, as one chooses.
Exactly, the subconscious doesn’t understand negatives. It just hears the words you’re telling it. So, if you’re doing a protection spell and you say “and keep me from harm”, eliminate the stop words and you’re left with “keep harm” lol. Always use something in the affirmative like “While keeping me and my family safe”. Eliminate the stop words and you’re left with 'keeping family safe".
Hope this helps!