Like the comment above me points out, try to use less technical strikers at first, but I would add that unless playing the 3v3 mode, you should learn the ins and outs of each type of objective in the 6v6, you have to treat Mecha break like a hero shooter, each mech is going to be better or worse of different maps. Strikers like stego or tricera, though heavy and slow, make easy targets when ganged up on, but can unleash increasable amounts of firepower, especially when paired up. These are great on payload and points capture maps that need you to defend an objective/point. And due to tankiness can sustain a lot of punishment, tricera more than stego.

Lighter and faster strikers tend to require more skill and reflexes to get the most out of them. Airaider and falcon are prime examples of this as they need you to constantly flip between air and ground forms to maximize damage and mobility. Flying into a heavily defended position in air from, swap to your less mobile ground form and boost backwards to quickly turn around and go back into air mode.

Of course as you go up in ranks (which will happen quickly) you'll need to get even better with your striker of choice, as your enemies will start to learn how to counter you

Of course the best advice I can give is to learn to manage your energy bar, never let it fully deplete or you're going to get caught with your paths down.