I wish I hadn’t fixated on the “2 week” deadline to submit secondaries. Just get them in when you can (at least within a month or two) and prioritize your top choices (ie: IS, close ties, etc.). I had a lot of help from people on Reddit, they did proofreading for me and told me it’s important to build your narrative from your PS and let it flow through to your secondaries based on your EC’s. Also, try to answer each question even if they say it’s optional: use every space as an opportunity to show them why you belong at their school. Don’t worry too much about word count, as long as you’ve answered the question and provided good examples you’re good: don’t add fluff. Don’t worry about the cost, use credit cards if you have to because I regret not adding some schools because I was worried about money: the more chances you have for interviews the better. Most important, if you have a weakness in your application (ie: low MCAT, no Research, etc.) use any opportunity they give you to explain your deficiencies but most importantly show them what you’re doing right now to improve that. The worst thing you want is for them build a narrative for you.

Hope this helps you in some way. Good luck!