Make sure your pitch is creative, detailed and still relevant
The first thing you should ask yourself (really before you even send out a pitch, but when following up too) is if the idea you're pitching stands out among the rest. If you're expecting a brand to pay you, you need to be giving them an original idea that makes it impossible for them to say no! This means it's 1000% necessary to go two steps beyond what you think is a good idea. It shouldn't be good, it should be SO incredible that that PR rep reads your email and doesn't hesitate in wanting to work with you. When I send my pitches out, I read and edit them at least two times through to make sure I can visualize the post I want to write - because if I can visualize it, the brand will be able to as well. The more creative you are and original your idea is, the more likely the brand will want to collaborate with you!
Another factor in following up is if you pitched a time sensitive idea. For example, if you pitched a brand with a dessert recipe for Easter three weeks ago but are now following up a week before the holiday, you're going to want to change up your idea; I've found that following up with a new idea has almost always proven to work and end in a successful partnership. Not every pitch will be time sensitive, but you want to make sure in a follow up email that if it is, you're addressing it!
This should go without saying, but in your follow up you should be just as professional as you were in your original email. Be professional, be courteous and show the brand that you have value to provide to them.
Follow up in the right amount of time
You don't want to be pushy, but you also don't want your pitch to get lost in a sea of emails! PR reps and media contacts get bombarded with emails every day - *especially* if their email is available online and easy to get a hold of. The most important part of being able to follow up with a brand is to not be shy or nervous to send that second email. You aren't being annoying - in fact, lots of brands will thank you for following up simply because your email got lost in their inbox or it was marked accidentally as spam.
When it comes to determining how long you should wait to send a follow up email, you'll hear a lot of differing times. Some people say to wait a month, some say to wait until the next quarter - but I've always gone by waiting a week or two at minimum. These brands' representatives usually have to pass along your pitch to other people on their team, their higher ups and so on. More so if it's a popular brand, so it's only normal to expect a brand to take a bit to get back to you. But after a week or two if you haven't heard back, there's NOTHING wrong with sending a professional follow up!
Most importantly, be persistent.
This circles right back into the fear of coming off as annoying to a brand. The worst that a brand can do is say no, or that they don't have room in their social calendar right now. But any answer is better than no answer, right? So no, there's no right time to stop trying! I followed up with a brand I was extremely eager to work with just a few weeks ago because I hadn't heard back and after a few emails, we have a collaboration in the works - ALL because I chose to follow up and not give up. To succeed, you must be persistent.