For a bella solo path how do I get the maximum scenes and interactions? I just don't want to make a choice somewhere that' blocks any dialogues or scenes with her?
Episode 1, making a joke when you first meet her can go one of two ways. Cute, or funny

Just be nice in general the whole game.
Clean the dishes, fix all the picture frames and paintings, check out the mask at her house in Episode 2. You can initially peek but don't continue. Try to kiss her when leaving the car.
Make a good impression in general by not fighting Troy, do good in class, don't insult cafeteria food, offer to buy her lunch, don't wear helmet. Go visit her in the library in Episode 3 after asking Jill out on a date. Obviously choose to stay with her at the end.
Stroke her cheek in the morning. Water her plants properly, clean the dishes. Massage her back, then arms, then ass. Splash her. Take it further with her in the pool in Episode 4.
Big spoilers!!!
If you're pursuing Cathy, do NOT get the blowjob in the car, it is a trap and torpedoes your relationship with Bella in Episode 7. Pair up with Bella during yoga, do not joke more than once. Get hot and heavy with her in the sauna with her. Paint her fence, and impress her with your pancake skills in Episode 5. Oh almost forgot, Bella does not approve if you punch Tyballs. And remember this is her favorite song.
Episode 6, you should automatically accept her help to clean your room. I recommend making sure the 1st floor bathroom is clean beforehand. Help her out in the library, accept the offer for more work. Oh, call Derek in the library for sure, then apologize. Stroke her hand. Either save the Ice Queen or join her.
Episode 7, if you don't hurt Tyballs then you can lecture her lmao. Have a nice romantic time at her place, it's sweeter to volunteer for the seniors, but funnier to clean the Pink Rose and Bella reacts to both. Have CHICK affinity so you can 69. Comment on her Cluck.
Episode 8, the date will be a disaster no matter what so don't worry. The second one will be better, and obviously choose her as the one you want a relationship with.
Jill will catch you guys no matter what. Oh, if you've already gotten permanent Neutral/CHICK affinity, don't flush the test results, so Bella can catch the cheater. And don't cheat yourself, she is very disappointed in you if you cheat on the test.
Episode 9, use CHICK affinity to dodge a bullet. Take a picture with her, recommend the funny/scary one. Pick her for Truth or Drink. Talk to the ghost. Either have an okay time in the Haunted Basement, or else let her get insulted during scary story time. Don't recommend body shots. She will win the costume contest no matter what.
Episode 10, as tempting as it can be, don't mock Tyballs and try not to stare too much at all the asses in yoga class, Ass Man. I recommend hanging out with Maya for a few reasons, one being that you can tell her about dating Bella and she is understanding about it. Up to you if you want to beat the Beer Pong Champ or let her win. Kiss her forehead. Shrooms are optional (assuming they're even available for you), she gets a unique scene.
That's all off the top of my head, in case I've forgotten anything.