Just do some MGE to get your dm up. What class do you play?

No, don't rely on MGE. It can be good for working on your prediction and shit initially, but later on probably it is best just for warming up.

From pub to comp, the transition is daunting.

I would recommend playing on a server with higher-quality players. I personally play on TF2Newbs #3 - 24/7 badwater. Provided it's the right time of day, there will be decent players in abundance.

Depending on the format you're trying to get into, find relevant demos or casted matches and watch them. Watch multiple. Try to get an idea of the game.

After that, I would recommend tf2lobby. Just hop in, try to get a feel for the format. But don't rely on it.

When you feel you're ready, advertise looking for an entry-level team or form one of your own from dedicated people that all get along and are willing to put forth effort.

i wouldn't follow the previous poster's advice of playing on a 24/7 payload server. payload maps don't offer up the highest level of competitive play and aren't used in competitions either. tf2lobby is what you're looking for. even when it's a complete shitfest, it's as close to comp as you'd get short of getting invited to the pickup group.

https://www.youtube.com/watch?v=hxeK7U1ExrU

MGE is just fine to practice with. It's a great warmup and the perfect arena to learn new tricks in and observe certain map geometry. Whoever says that MGE is not useful hasn't used MGE to it's fullest potential.

If you want to transfer from pub to comp, make a friend in the competitive scene that can help you out. Find a mentor in the class you want to main, and eventually work your way to finding a team (or eight/five other friends).

As far as practice goes, tf2lobby.com is good. Once you get the hang of that, go to IRC and go to #tf2.mix.nahl or #tf2.mix- then #tf2.pug.nahl / #tf2.pug.

Hope that helps! Contact me on Steam if you have questions at KaiThePhaux.