you should realy learn to hold B solo with backup in spawn like SK is playing with face B site and robban as backup. So good if you can pull it off since A site is harder to deffend then B so if u can be 3,5 att A it's easier.
So try do download som hltv demos of SK on inferno or pov on face.
His also amazing at inner on train.
Just 2 tips if you're gonna hold solo.
1: Information and communication with your backup is the key.
2: Don't die to easy and if you die you need to know that your teammates have plenty of time to rotate, so you need to oeak the banana.
the best b-site defenders of all time was for sure mje and zonic back in the the mTw-year. just watch mje at ramp(nuke) and inner bombsite(train). he is an good example for a B-site defender at any map