So i can come up with riffs and whatnot that i like, but i can never seem to make any that would fit together well in a song. anyone else have a similar issue? any tips to write better, or is it just something i need to work on more?
Listen to CKY.
I had that problem when I was first starting out. What works for me is when you have a riff, try to come up with a chord progression that you can play underneath it. If you have a good understanding of chord progressions and such, you will become very good at this. But if the "technical" stuff isn't for you, you can just fiddle around alot like I did and kinda figure out what works and what doesn't. However, I ended up studying theory anyways, so I really reccomend starting there. Lemme know if you'd like some sites and such to help you with this. Cheers!
You might be surprised to find out how well playing with others affects your songwriting. Go on...try it!
I know the feeling. Ive been having that problem too and I just started to get out of it within the past month. My advice is to not force anything. If you just can't seem to get anything to fit right do not push it too hard.

About a week ago I was messing around with this chord progression I made up in the past month- it was just a 4 basic chord progression that I would sometimes switch up. I don't know much at all about music theory and stuff so I just do what sounds good and feels right. I didnt ever really decide I was going to make a song out of it, I always just thought it would make a good one somehow because I could never get anything to fit.
Then I was playing it and I randomly decided to try a different strum pattern which helped me really get into it and I just started singing what words I thought would fit the melody and the basic idea I wanted to sing about. After a verse or 2 I would write them down and sorta fine tune them. Now I have it about half written and can't wait to finish it later today.

This may or may not help you with your riff problem but atleast I tried!

My Advice: Let the pieces fall together. Don't sit down and play with a goal of having a song when youre done. When you are playing and having fun with it and getting into the groove, you can feel what will work. atleast that is what works for me.

Good Luck