How do I actually make a budget?

It has been really hard to stop just buying things when I “need” them and to really think about each purchase that I make. There have been times in the past where I knew that I was spending way too frivolously and that I was getting in debt (ahem, spur of the moment trip to Greece), but most of my spending really always felt pretty justified. “My jeans ripped so I really did need a new pair.” “I need a caramel macchiato from Starbucks if I am going to function at all today!” I knew I was making a decent, stable living, so it didn’t seem like I was being irresponsible by spending my money this way.

That is really the hardest habit to change right now. No new jeans. No Starbucks. And especially no trips to other side of the country so my boyfriend can watch his favorite football team play at home. I’m getting the hang of cutting out the spending I know is frivolous, but I still can’t seem to actual make a budget that includes everything. I have no idea what is realistic to budget for the things that change every month. My electric bill can be $40 or $70. If only drive to work and back, I really only need about $100 for gas every month. If I make a few trips over to see a friend or drive farther than normal for any reason, I could need $200 for gas. How do I account for things that just ‘pop up’ in the middle of the month? I just got invitations to two bridal showers and a bachelorette party dinner for this month. I didn’t account for buying gifts, but these are fairly good friends.

I know that having a budget is going to be key to really getting done with my debt snowball (baby step 2), but I just don’t feel like my spending at the end of the month is even close to my budget at the beginning. Dave says to spend every dollar at the beginning of the month on paper and on purpose. I’m trying, but so far I’m really struggling.

Does anyone have advice on what has worked for them?