Looking at Frontloading HQ, Beto needs Iowa and good showings in the following three states: NH, SC, and NV. He should hope for a win in at least one of those three.
Looking at Super Tuesday, Texas should be a lock for him, which will counter likely-candidate-Kamala’s strength in CA, which will be a Super Tuesday state this year. Oklahoma might be good ground, but there’s lots of ancestral Dems that may be unruly (see also WV).
Other Super Tuesday states: Alabama, Massachusetts, North Carolina, Tennessee, Vermont, and Virginia.
Massachusetts and Vermont don’t seem like fertile ground since Bernie and or Warren will likely win there. Alabama might go for a black candidate, but if say Harris and Booker can split that vote, Beto could have a shot. Tennessee, North Carolina, and Virginia could be in the running too. Depends on who the establishment candidate seems to be (especially for VA).
Louisiana is the next Saturday. This is a state Beto should focus on given its proximity to Texas.
The following Tuesday has Michigan, Mississippi, Missouri, and Ohio. These (especially the non-MS ones) could be good for Beto.
March 17 brings Arizona, Florida, and Illinois. Beto should win 2/3 and then he’d be in a good position to start winning big across the board as more people drop out.