Selenium Test Project Management

I have general questions about selenium web project management, below is an example: my question is how to manage these test cases (its only 3 for example, real test cases are over 1000)

Is a class good for sub-tests, for example a class for logging, and all tests related to logging are under this class?

Are there conventions for writing and managing test cases?

Thanks everyone.

I create class with tests like:
        @Test   //Test1
        public  void logInFaildTest() {
            GridTest gridTest = new GridTest();
            WebDriver webDriver = gridTest.getWebDriver();
            String url = gridTest.getUrl();
            LoginPage logIn = new LoginPage(webDriver, url);
            String userName = "user";
            String pass="pass";
            logIn.login(userName, pass);
            WebElement errorMsg = webDriver.findElement(By.className("dijitToasterContent"));
            String actual = errorMsg.getAttribute("innerHTML");
            String expected="Incorrect user name or password. Please try again.";
            assertEquals(expected, actual);
            webDriver.close();
        }

        @Test
        public void loginSucsecc()
        {
            GridTest gridTest = new GridTest();
            String url = gridTest.getUrl();
            WebDriver webDriver = gridTest.getWebDriver();
            LoginPage logIn = new LoginPage(webDriver, url);
            String userName = "user";
            String pass="pass";
            logIn.login(userName, pass);
            String actual = webDriver.getCurrentUrl();
            String expected= url+"#lastmile/";
    //      webDriver.close();
            webDriver.quit();
            assertEquals(expected, actual);
        }

        @Test
        public void accountLock()
        {
            GridTest gridTest = new GridTest();
            String url = gridTest.getUrl();
            WebDriver webDriver = gridTest.getWebDriver();
            LoginPage logIn = new LoginPage(webDriver, url);
            String userName = "user";
            String pass="wrong";
            for(int i=0;i<11;i++){
                logIn.login(userName, pass);
                logIn.clearFileduNamePass();
            }
            WebElement msg = webDriver.findElement(By.id("dijit__TemplatedMixin_0"));       //block message
            String actual  = msg.getAttribute("innerHTML");
            int splitIndex= actual.indexOf(".<");
            actual = actual.substring(0, splitIndex);

            String expected= "Your account has been locked";
            webDriver.quit();
            assertEquals(expected, actual);
        }
    }