I usually charge 100% in advance to avoid issues with no payment.Also today working on GBP must be constant even you give a push to results in 30-40 days when they take drive nobody later can get it up. So if is serious business they will invest money monthly on long run at least year and half. Why? because in 2-3 months they will be holding many top 3 spots on different keywords , but if the call off they will loose rankings as well. I had client who change me and hire different angencies and monitor my way of work in 3 months when i stop with work they lost all cases. PI (personal injury lawyer) niche i was generating about 15 cases again signed cases, and they monitor my work with opinion that can later mimic by their seo teams or thirth party side. They lost all cases on second month and positions.
So you need to have a way to protect your work. So when I start to work I'm telling this to each client so to not have misunderstanding later.
