Just try and declutter often. Donate things you don't use, and don't waste your time trying to have garage sales. You'll give up a weekend for a $75 profit. Bless others by donating. Inform grandparents you want to avoid excessive toy clutter, and make it clear what type of gifts would be best for you and your family.
If you personally are a fairly well organized, decluttered person, it will translate in how you parent. You'll do great.