I agree with the top two posts,
I would get a secured Discover card, and would try to deposit the highest amount available. (it may cap at $2,000 but I'm not sure).... it can graduate to a regular card in as little as 7 month ... for some people longer.... but your funds get returned, and your card 'graduates". Use it, pay it.... at times even before the bill cuts, making a few payments a month.... but it shows ablity to use & pay quickly.
I would also do a "self lender loan" which is often offered by local credit unions for the highest amount possible ( also often $2,000 )... they set up a "loan" but you make a deposit every month..... like a holiday club... but it shows the loan being paid, after 12 months you get a check for the amount. ( some fees are charged and calculated in ).... but it's well worth it... but shows up as a loan, paid in time, and then paid in full. this will also help your credit.
The third thing I would do, maybe a few months after the top two, is.... if you drive apply for a gas card ata convenient station. The top three will boost your credit..... then you apply for other cards...... and you're off to the races.
Take it slow.... conservative, don't apply for too much too soon, you don't want wasted 'credit hits" for declines... but after the top three.... you're off to the races...but remember building or re-building credit is not a sprint.... but a marathon.