Are there do's and don'ts when mixing materials in a kitchen.?

Please, don't paint your cabinets unless they are really torn up beyond any other salvageability and/or they have some character to them like routed edges and frames!! When people paint over very plain cabinets, it looks cheap. If they look dull, re-stain them or clean them with TSP and then put a fresh coat of poly over them. You don't even need to unhang them for this often. You can send them away to a "strip and dip" wood shop who will strip and refinish them for you. It is very inexpensive compared to replacing them or the value you will lose by painting them.

Try to not be too busy is the main rule. Pick something to be consistent with. It is really helpful to make a color/material board the way interior designers do. It will keep you on track. You can get samples of materials and pictures and put the stuff together and then see how it will go together on the board. This is the number one way to avoid a costly mistake is to make a collage first. If it looks ugly on the board, it will look ugly in your kitchen.

Also work with your existing materials, not against them. If your cabinets are a warm color, find a warm counter top and tile.

Make sure your appliances match in color.

If you have a bronze faucet, don't get a brass lamp.

It is great you are doing as much as possible...but...you really should have a total room plan before starting, so you know exactly what you will end up with. You need to start somewhere..cabinets are a great start..choose what you like. Get samples of every choice..flooring, cabinets, countertops, paint. Create a picture board ensuring you like the whole look together then proceed with your projects knowing you will love the look once it is completed. Google kitchens for some ideas. You should decided on your appliance colours, faucet, sink finishes too.

well no matter what you do i'm sure you will be happy you did it yourself ,but i will agree with the person before me yes indeed keep all you metal finishes the same no matter what you pick. so if you picked brushed finish for your sink pick the same for your lights, handles ect. don't get to hung up on this go with that too much, pick what you like ! you will be the one living with it. I just did my kitchen this winter in the tuscan theme on a tight tight budget that would make a penney scream (lol) and everyone who has seen it loves it. good luck !!!