For instance, car maintenance; Your car will probably need at least two new tires and 2 oil changes in 2018, divide the cost by 12 and set that money aside each month. Also holidays/birthdays, make a quick spreadsheet of the major gift holidays:
February 14 Valentine's Day
May 13 Mother's Day
June 17 Father's Day
December 25 Christmas Day
plus any birthdays, weddings, anniversaries, and baby/bridal showers you need to buy a gift for, estimate an amount for each event and divide by 12. set that money aside.
I also plan ahead for holidays that are less gift-y but still end up needing purchases like costumes, or pot-luck food, or just going out with friends.
March 17 St. Patrick's Day
May 5 Cinco de Mayo
May 28 Memorial Day
July 4 Independence Day
September 3 Labor Day
October 31 Halloween
November 22 Thanksgiving
I've been successfully budgeting for a few years now and I find that planning ahead for these categories helps a lot! good luck! :)