Interior decorators (in my opinion) have their OWN personal tastes, no matter what. So unless you want their tastes in your home, it's better to do it yourself & not hard at all!
My only deviation from this is if you're doing a major renovation to a room such as a kitchen or bathroom. I hired an expert company for the design & layout & to make custom cabinets specific to my space, BUT I picked out all colors, tiles, appliances, countertops, hinges, etc. on my own! I also must have gone back & forth 2 dozen times with the layout to ensure I got what I wanted and liked!
I just Google colors, styles or pieces that I like and usually similar stuff will pop up in your search & you can go from there! This would be if you're just doing maybe paint, some furniture and/or accessories in a "refresh" type of redecorating. And obviously much cheaper than a gut job to a room. Start with a wall paint color, and once you have that, everything will fall into place! And most importantly, have fun & don't worry what other people think. You have to live in your space, so pick colors you love!