You can also apply for 2 or more credit builder cards (these often have low limits, and are a great way to quickly boost and build credit).

If you try to arrange a seller credit outside the sales contract and out of the lender's view, I think you are playing with fire. 

Fill out an application or complete credit/background check, no. 

Because it’s going to cost at least $50 in credit card charges on a $2k/mo rental..Are you allowed to charge extra for credit card payments, say 5% surcharge so people are discouraged?

-- AND the practical thing: Clean up my credit rating by (a) increasing available credit (without any hard pulls), and (b) clearing as much open debt as possible to reduce credit utilization (and then keeping it clear!).

Quote from @Jimmy Rojas: Im a first time homebuyer, i been 1099 for 10yrs now, total monthly expenses $1500 , no debt, bring in $5k a month, experian credit score 745, looking to borrow no more than $200k maybe less, ideally $15k down payment , %6 or less interest,  monthly payments $1500 or less, what are my options and what route should i take. 

Quote from @Geoff Prickett: Anyone recommend a great bank or credit union for working with Series LLCs?

I have a few business card but my favorite is PSECU personal credit card .

It's gets cumbersome when you have 1 investor with 5 properties not in an LLC on credit then these CLAs are a mile long for no reasonThe easiest way around this is to request a credit supplement with your credit provider verifying the last 12 months of payment history, instead of dealing with the horrible servicers.. lol But yea it is a bit more paperwork.

But generally speaking, managing your credit score is a common task for real estate investors - especially for those who make use of credit in the purchase and rehab of properties.