If you get onto the iSecretshop platform, they have several MSCs in my area who have shops and you can complete them in an app, which makes it kind of easier because you can just walk away from the place you just shopped, go somewhere no one can see what you are doing and complete it right then and there. Other platforms have apps as well, but some of them don't work that well or only let you partially do things in the app.
I'm just celebrating my first month of shopping, but I just kind of jumped in like a crazy person so I have done about 30 shops along with having a fulltime job lol. As a newbie, I think cell phone shops for places where you are not a customer are the easiest. There's one on iSecretshop I've done a few times that pays 9 bucks. You just go in and ask what the associate recommends, based on the guidelines. When I did some, it was best smartphones and smartwatches. They don't pay a lot, but it helps get over that nervousness of being incognito, remembering what you are there for and remembering all of your "lines" and such. Read the guidelines carefully, but you typically don't have to give them any information other than maybe a first name. If you can find some near where you live or work it might be worth a try.
As a newbie, one challenge can be doing shops where you have to pay some of your own money for something. You typically don't get paid for a month to two months for most MSCs. Depending on your financial situation, you might want to pace yourself on those at first until pay starts coming in from the shops you've already done. For that reason, you might actually want to pick up a few easy ones in December so you do have a little pay coming in in January.
Trendsource pays the fastest of the ones I have worked for- There are pluses and minuses to Trendsource. They always seem to have jobs available, and I think that's because they don't pay that well. I've done several grocery jobs for them that are pretty tedious and take a lot of time on the report, to the point where you are barely making minimum wage, if that, but you do get paid within a couple of weeks, and everyone needs groceries. I'm a month in and they are the only ones who have paid me so far, although I have some other paydays I am expecting soon.
Good luck