I'm the owner of a family business, but I am receiving no salary and I am unemployed. What can I do to increase the likelyhood of getting a visa?

I will try to summarize your situation:

1. You want to visit your boyfriend in the UK.
2. You are supported financially by your parents.
3. You own a business, but are not receiving a salary from that business. It is not clear from the comments if the business is registered or not (ie, do you have a business license or are you a freelancer); and if you own the business what is your equity in the business (are you getting a share of the profits? are you listed as an owner in the legal documents of the business?)
4. You have been accepted for a masters program in the UK, but have yet to apply for the required visa to attend the program; which starts in September.

Now, given all the above - the simplest way to move forward is:

1. Apply for a student visa based on your acceptance letter.
2. Provide the financial details of your parents as they will be supporting your studies while in the UK.
3. Provide the other normal documents required for such a visa (as you have previously applied for the same, you should know exactly what is required).

Trying to apply to visit your boyfriend is going to be very difficult:

1. There is nothing that ties you to your homeland; but there is something that is a strong reason for you to stay (or overstay) in the UK. You have a boyfriend there that is willing to support you.

2. You are (by your own admission) unemployed; and are not receiving a salary.

3. The fact that you own a business; but somehow it is clear that you are not being compensated for it. Perhaps its a family business and you just have shares in it, but aren't actually an employee of the business. In either case, this is not compelling ties to the homeland.

All these will be difficult to overcome if you are applying for the purposes of visiting your boyfriend, and trying to convince the officer that you are not going to immigrate.