Stay true to who you are and what you'd like your brand identity to be. Start off by asking yourself what adjectives you would use to describe your business. From there you can develop your tone and voice, then add the creative element and add colors that are associated with your business and those adjectives you picked. Next, start thinking about fonts, what main font you want your products/ marketing collateral to display. Using google fonts will help you match fonts that look great with the one you chose. Look at websites in the same industry as you, create a list of what you like and don't like. Start documenting all of these little excerises and before you know it you have a skeleton to brand guidelines!