This is a general courtesy rule but one that is applicable to all professions. Holding an open house is quite stressful and usually agents work solo in circumstances like this, so they’re very busy on the day.
You don’t have to wear a suit but it’s important to look presentable. It shows you’re keen to secure the property and that you’re taking the application process seriously. If you show up looking like you mean business, you could increase your chances of success
Being pleasant rather than pushy can put you in the good graces of the agent.
Only submit the necessary documents. It’s fine to have any additional documents you think you might need on hand, but only submit what the agent asks for. If you’re ready and waiting when they arrive they might remember when the time comes to choose a tenant.
Your housemates don’t have to attend the property inspection (although this is preferable) but you need to get their full and completed application and references. If you have a complete set of documentation for all members of the household you’ve got a better chance of being on the top of the pile.
If you’ve submitted an application and you haven’t heard anything 48 hours later, do send a follow up to the agent.
Let them know you’re very interested in the property and that you’re happy to provide any additional information or references they might need. They may well be trying to decide between your application and another candidate and if they receive a pleasant message from you, it might just put you at the top of their list.