You can increase your credit score but it won't happen in just a few weeks. If you continue to pay your debts back on time and never miss a payment your credit score should increase naturally without doing anything else.
Be aware that taking out too much credit in too short of time or applying for new credit can actually harm your credit score and cause it to lower instead of raising it.
Just make sure you never miss a payment to a loan company or credit card and your credit score should start creeping up when they report your on time payments.