lucifux,
Welcome to CivFanatics.
Firstly, this is a game where you (a.) can't often rely on 'cookie cutter' strategies to deal with every start you're handed, and (b.) there's 'more than one way to skin a cat' in that for every problem there are multiple solutions and these may be leveraged in different ways to varying degrees of success.
Secondly, I note that you are presumably playing with 'vanilla' Civ, as Frederick's traits have now become Philosophical and Organised under Warlords, and you have not mentioned the unique buildings that are another Warlords addition.
Tribes that start with Mining should generally look seriously at Bronze Working as a first technology. England with Fishing can start right away on a Work Boat and grow London if settled on the coast near seafood.
Both leaders start with the Philosophical trait, which means that you can get a turbo boost along the technology tree if you're happy to work towards running specialists and picking up early Wonders that each contribute

points. Getting to Writing building Libraries and running Specialist Scientists opens terrific lightbulbing (burning your Great Person on technology advancement) opportunities. Many players use Great Scientists to research several technologies towards Liberalism (Philosophy, Paper, and Education). Lightbulbing becomes increasingly effective from Prince level and above.
... because you're playing 'vanilla' you can also look at runing Specialist Priests (req. Temples) to produce a Great Prophet that can be used to research the bulk of the highly desirable Civil Service technology (ref.
Sulla on views on Civil Service).
Lightbulbing is also an effective way to pick up many of the later religions (Philosophy > Taoism, Theology > Christianity, Code of Laws > Confucianism).
Frederick's Creative trait generally will protect many of your early cities from flipping, and will allow you to quickly work all 21 tiles in a fairly newly settled city because of the +2

per turn, meaning borders will pop within five turns under normal playing conditions. Cheap Theatres are a nice extra if you're concerned that a captured city is under big cultural pressure and has happiness issues (to counter 'We yearn for our Motherland' / 'War, what is it good for?' unhappiness).
Elizabeth's Financial trait is powerful, and combined with Fishing means that coastal tiles and Lakes start out 'more than useless'. Once Cottages grow, or even Cottages settled on rivers from the outset, their extra commerce will help keep your economy in respectable shape. Elizabeth is well suited to both a Farm Economy (building Farms to feed Specialists) and a Cottage Economy (relying on Cottages to provide the backbone of your empire's commerce) and can run a transitional (beginning out with a Specialist Economy and veering towards a Cottage Economy over time) or a hybrid economy (a few cities run specialists, some focus on Cottages) successfully. The Redcoat is a terrific unit - like 'baby Infantry'.
Their weaknesses are the lack of strengths that the other leaders have! In both cases their unique units are 'generally' late game units, where you might have 'missed the boat' in terms of leveraging your UU to own a huge chunk of land. The Romans are a striking example where you can amass Praetorians and little can stop a ferocious onslaught of these guys when they attack en masse. That's not to say that you can't do some pretty severe damage with a bunch of Axes ... or Maces/Catapults/War Elephants ... so you don't have to wait for your unique unit to arrive in order to take a stranglehold on the game.
Keep reading! There are loads of guides in the
War Academy - such as
Traits, Warlords, and Synergy (which deals with 'vanilla' traits also), or check out some of the community walkthrough games such as the
All Leaders Challenges. aelf's also done a thread;
A comprehensive UU guide (the updated thread) that addresses the Redcoat and the Panzer.