If you've been thinking about a room addition or a dormer extension there are a lot of steps involved but it need not be overwhelming. First you need to decide on the room size. A good rule of thumb is to oversize it by at least ten percent. The biggest remodeling mistake people make is designing a dormer project that ends up too small for the family. You can't stretch it later on so be generous up front when you add a room or a second story addition.
Secondly, retain the services of a good architect. Though it cost some money in the long run you will save with a more efficient design and in most localities it is a requirement to have the plans certified by an architect. This individual can also supervise the job for you as well although usually for an extra fee. You do not need this expense to do a good kitchen design however. A kitchen makeover is a separate topic.
Once you've settled on a home remodel design you would be wise to consider any "green" alternatives that you can build into your project. For example, more and more room extensions and garage conversions are utilizing blown in cellulose insulation as a green thing. It is non toxic and eligible for and energy audit rebate. Solar panels and sunroom are becoming increasingly popular and are eligible for tax credits and rebates. You save money in the long run and they add value. Another point- do not skimp on the lighting. It is so much easier to run the wiring before sheetrocking than six month later when you decide the room is too dim. To brighten up further - add skylights. These come in tinted and low E glass models which filter out some of the suns rays and save heating and cooling costs.
In home remodeling the question often arises regarding wall thickness. As a basic rule of thumb 2x4 walls are preferable when there is a need to blend into existing structures. Insulation can be beefed-up to meet existing energy codes and insulated vinyl siding can work like a charm to turn any home remodel project into a green dream.
The actual construction should be done by a well known company in your neighborhood. Check out references and trade credentials. Opt for a Certified Remodeler if there is one in your area. These folks go thru more testing and training than the "I got a license" individual. Ask to see a portfolio or DVD of completed jobs. A good home contractor or master General contractor is worth their weight in salt.
Lastly, depending on your part of the country, always use doug-fir plywood and not particle-board when possible. It costs a little more but makes for a better job. Even in a garage conversion or finish basement project the added value is cost effective.