General business tip 1: Action speaks louder than words, so don't get stuck on planning and what if's.   

General business tip 2:  Realize you are going to have to sell.  Whether it's product or services when you startup you have to be the sales person, so be prepared.  If you have not sold before begin your training now.

General business tip 3:  People like to do business with people they know, like and trust.  The latter are the most important in the beginning.  Not everyone is going to like you, it's business so don't take it personal.

General business tip 4:  Not all customers are good customers.  Evaluate your profit, relationship, pain level with customers and realize sometimes  you have to fire one and move on.

IT Systems tip 1: Use cloud resources as a startup, Office365 and GSuite will do most of what is need and most accounting software is available online.

It Systems tip 2: Don't buy more than you need, its easier to "get by" in the beginning than spend $'s on product your not using.

It Systems tip 3: (general business tip as well) Be careful when signing up for trial software using your credit card.  Its easy to forget to cancel and they bill monthly, these add up.  Consider canceling your debit/credit card and getting a new one issued at the beginning of the year, the vendors who are billing you that minimal amount will let you know asap you missed a payment! This brings the little charges to the top.