Sigilcraft:
First of all, sigil shape doesn't matter almost at all except to the person using it. The only problem would be if you copied (purposefully or accidently) another sigil.
In essence there are three things to focus on when utilizing sigilcraft:
Getting the most focus on the sigil
Getting the most will into the sigil
Making the sigil part of your intent
Focusing on the sigil while putting your will into it ensures that the most energy goes into it as possible vs just getting pushed out of your body. The more will that goes into the sigil means the more energy the sigil has to work with. Making the sigil part of your intent means that more of the energy in the sigil will be dedicated to the purpose of it. This means that continuously thinking of the purpose of the sigil while putting will/energy into it will put will make the sigil work better than just stating its purpose at the beginning or end. Now, a few mythbusters:
Burning your sigil can help, but is not necessary. The best thing to do is to have it in a place you will see everyday until you are done with it so you can put as much will into it as possible.
Jacking off to your sigil is weird and creepy. Don't do it. Although if you feel like you need to, it does actually work quicker than other methods, but I would rather spend an extra 10 minutes staring at the sigil.
Sigils link to things and sigilcraft sigils are no exception. They link to the construct which is created to do your intent you put into the sigil.
Not all sigils are made through sigilcraft.
The practice of sigilcraft has a lot of misconceptions about it so be wary of them.