or a contract of sorts
Bit difficult to be a contractor without a contract! You may get advice from people with actual experience, but from observing over time it seems the normal method is to set up a company, with you as the sole employee, and then the contract is with that company. However, as RHRP says, the laws of the country you are in will have a significant bearing on how you go about doing business, particularly with tax. Some countries take a very dim view of self employed people working for a single client, as it can be perceived as a way of avoiding the person being employed directly as a means to dodge various obligations that would then be mandated. e.g. social security payments, leave entitlement (including paternity/maternity paid leave), redundancy pay etc etc. Plus the contractor is also able to gain tax benefits by reclaiming costs associated with the business, such as costs associated with a vehicle, office equipment etc. Have a look through this thread as an example.....
https://www.pprune.org/archive/index.php/t-591436.html