To solo mine, you must have enough Gridcoin to stake and earn rewards. You should have enough Gridcoin to stake about once every month, which is around 5000 GRC. Consider following the pool mining guide if you do not have 5000 GRC
Don't Want BOINC rewards?
Switch to the Non-Cruncher guide. You do not need to install or run BOINC in order to use GRC as a cryptocurrency.
To earn Gridcoin, you need to crunch whitelisted BOINC projects. You must install the BOINC client and select several BOINC projects.
For getting Gridcoin, see step 3. You can also start out by pool mining, which needs no Gridcoin to get rewards.
BOINC video introductions: