First, expansion of a room can be difficult and costly, so think about whether that is something you must absolutely do. If you are trying to stay on a budget then it's best to work in the confines of the space you have. If you can spend more on expansion, then by all means. But it's best to get some estimates before going ahead with the work.
Two of the most important parts of the kitchen, in that they take the most abuse, are your flooring and cabinetry. The floors are being trampled over all day, with family, friends and guests walking in and out. And cabinets are constantly being touched, pulled, and otherwise manhandled constantly. So it's a good idea to splurge a little more on that part of your kitchen renovation. You want these two parts to be the best quality so they last a lot longer.
Because of so much rearranging, sometimes the best thing to do with the kitchen is to gut it completely before starting work. Chances are you'll need to deal with new plumbing, re-wiring and completely redoing the floor. Getting everything out of the kitchen and out of your way is the best way to get started on this.
The most expensive appliances don't always mean the best, so keep that in mind before buying. Do your research on everything, from the oven to the microwave, before making any major appliance purchases. You want a kitchen that's going to work optimally from the get go, without having to make future changes too soon
Kitchen renovation projects, if small, can be do-it-yourself projects. But you have to know where the line is drawn. Sometimes doing it yourself can be more money spent and the higher the chances of a mistake happening, especially when it comes to plumbing and wiring. That can be very hard (and dangerous) to do on your own. It may be best to just leave that to professionals. Research for local general contractors and see who can work within your budget and time constraints.