I am signed up with about 32 companies. I signed up with everyone who was posting in this area but a few no longer have assignments locally. You never know, so I check their boards now and then. There are 4 that give work monthly, no one weekly. I also do some with the apps which only works if you are nearby or there anyway because most don't pay enough for the drive. Many of the assignments here pay $5-$10 and a few $12-$15. Once a month I get a $20-$30 and once a quarter a $35-$50.
You will meet all kinds of schedulers and editors. I have done over 2000 shops and you will get to know what each person is looking for. I have a nice relationship with many schedulers and some schedulers contact me when they need a "favor" or an assignment done correctly and quickly. The key is to complete assignments according to the guidelines and if you need to change an assignment let everyone know as soon as possible. Once you are rated as a good shopper you will have a little more flexibility if you need to change something and everything will continue to get easier/
Schedulers have already described me as reliable but I don't have that number under my belt.
If I do a favor for a scheduler then they want to pay me even less the next time. It has made me a rather a "hard nosed" person trying to work with schedulers. In my experience he who cares least controls the negotiations.
Don't send 17 emails about a shop. Don't call repeatedly about a shop. If a scheduler sends an email to you and you can shop the location, send an email. Offer to do other shops in that area. Most importantly, do the shop your assigned by the due date.