i really wasn't sure where to post this question, so i posted it here. if i have posted it in the wrong area please move it to the right area....i have been thinking of trying to sell my art work for years. so far i have not had any success of doing that. but here is my question. if i wanted to do a painting with gimp and then try and sell it, i would have to make prints of that painting...so my question is, would i have to make my picture a certain resolution in order for it to come out right when it is printed?....i have a ups store near my house and i was told by a artist friend of mine that they would be able to print a picture for me at a small cost...that's what i had in mind. but i wasn't sure if my art work would sell or not....hope someone can help me with this...

minimum of 300dpi as far as i know

That's right. I would say 300dpi at the very least. Do you have the whole CMYK issue resolved?

First of all I'm NOT an expert on this but I've done some reading.
Printers use CMYK and not RGB.
Digital photo's come with an "exif" file embedded.
This file will be used by the printer to convert it to CMYK.
Your paintings won't have such a file.
Esper is right about resolution.
I guess it's best to talk to the printshop people.
Getting colors right in a print is not an easy thing.
Starting artists in my area usually organize an exhibition to promote their work.
Maybe cheap possibilities exist in your neighbourhood (churches,community centers etc).
Gerard.

Too hard answer to the main question if your print could sell

I use deviantart that has a not very convenient but totally risk-less print service :
not convenient because if they sell the percent to the author is minimal, but risk-less because prints are done only if ordered and payed so are no risk

Anyway till now (in in 8 mouths)i didn't sell a single print

If you have no local consumer maybe you can try something similar, if you see that you are start to selling you may look for something more convenient (there are several alternative...also to print on t shirt and object (as http://www.zazzle.com )

Or even take the risk to invest some money obviously if you order a good quantity of print and pay cash, your percent would be much bigger but would be bigger also the risk to not recover your investment.

In my opinion if you have a site or gallery that attract hundred thousands visitors then good chance you may sell some prints, if less will be much less probable....

and with about 10.000 or 5.000 visitors, (the last is my case) almost no chances

About printing image size is very relevant and should always much , much bigger of the size of the print

you can get a lot of information on requirement for print (don't forgot image size : crop is a extra process and will addd extra cost and anyway most wish standard format ) here

http://help.deviantart.com/printsservice/

that is what required by DA print service but most of info are valid also in general

Thanks for the info Photocomix, but clicking on the first question should I submit files in rgb or cmyk, Da only accepts rgb, but no explantion.

Yes not all the printers accept only CMYK, but many do

Anyway the most relevant info are about dpp and image size...just to give a idea to print at postcard size is expected more or less a wallpaper size.

About quality png and tiff are equivalent but for some reason many printer seems to prefer tif