I can't say what works for others. I do still beleive that assets and business revenue (sales) will take you the farthest.
However, keep your credit spotless make good use of your accounts and pay them off quickly. Build with AMEX because if you have a good personal profile with them then aditional cards and lines of credit can be a soft pull even on the business side.
Before you ask for that much in credit try to build your credit lines and then don't open new credit lines for at least 6 months. Just build those you have. Since you don't have a large business yet you need to keep your inquiries down on your personal reports as this is what they will be looking at.
Since many lenders are going to want to use an app to "link" to your business bank account like Yodlee or Plaid, get multiple accounts and move the money between them both in ACH transfers and checks deposited to show a lot of activity. Change up the dollar amounts. I don't think the algorithms look for who the ACH or wire comes from as banks display it differently. For me I have about 3-4 deposits/3-4 withdrawals per month.
If you do an SBA loan I think you can get there. But don't do a line for credit for startup funding. You need a longer "term" loan.
