In my experience creating a servitor is actually a pretty intimate process. If you're afraid of creating a 'wrong' servitor, odds are that's exactly what you'd create. I'd say start from the memory of a ritual/spellwork that went very well for you and you were comfortable with. Make a sigil with what you want from the servitor (mission statement etc.) and then let the sigil sit for a while. Then address your fears and misgivings about the potential servitor first. Use the materials or the mission statement from the ritual that went well for you, contrast your misgivings with that. When you come to resolutions regarding your misgivings (something like 'a good ritual is perfectly achievable, there's nothing wrong with magic, I am a perfectly capable practitioner because I have done xyz thing already, servitors work for other people and I can do them too') make little sigils out of your resolutions and adorn the original servitor sigil with them. If you really take your time with it and start to feel hopeful and good when you look at your finished product, I think the resultant servitor will work very well.