I guess I have an issue here. Sometimes, I'll be winning my lane.. However, then the lane opponent decides to roam. I'll ping missing with the mia ping but usually they get a couple kills regardless and catch up. Should I follow them if they roam? Push tower? Sometimes pushing tower doesn't cut it, and the jungler will show up to protect the tower. Give me some bits of advice.

Roam if you can make a difference in another lane, or push your tower, or both. If the jungler shows up to protect the lane, your jungler is free to either countergank, protect the lane from the roamer, or apply pressure in the remaining lane

First, a ward works miracles. I assume you are top lane...
You probably want to tag along. count to 10. If they don't show up in lane, ping like mad and do whatever you can to get to mid. It helps to have a mobile top lane, such as Singed, nidalee, rumble, etc. in other words, if you are darius top, you are going to have a bad time. Start taking notes and getting a feel. I truly believe each lane has its own vibe in every aspect.
in top, its jungler "presence" that you cannot see but can feel from the enemy laner's movements, trading, and specific knowledge on how the jungler chooses to gank. (If you are up against enemy shaco, then expect an aggressive gank by your 10th/20th creep if you play somewhat offensively. Yeah roaming is a bit hard to get a hang off. I found placing a ward behind the baron wall helps as some people are just incredibly predictable. Remember that some lanes, you likely wont win. if your jungler is off helping bot lane take dominance, then it is ok if you lose lane. It is a trade off your jungler has chosen and you should try your best to make sure the enemy jungler supported lane doesnt take an inner tower or go more than 3-0. hope this helps.

Make a judgment call based on these four conditions

1. Can my teammates survive/escape the gank?
2. Do I have an opportunity to take a tower?
3. Is the enemy setting up for an objective by roaming and/or will there be a big team fight?
4. Would my team get kills if I followed?

If you get yes, yes, no and no, then just push lane. If not, follow the roam.

If you're winning and they just roam, shove your lane down as hard as you can. Make them pay for not being in lane.

here is a list of the best actions to take in such instances:

1.- talk in all chat about how much of a ***** your lane oponent is because he got scared and ran like a little *****
2.-rage to your teamates, for feeding, make sure to remind them how stupid and bad at the game they are.
3.-insult the jungler for defending, and tell him to go the **** back to the jungle
4.-ragequit.

jk, id put a serious answer but a lot of people have said what i would say so its kind of pointless.