It is a really easy engine to work on. if you plan to ride it off road more than on the road you are going to figure out really quickly that the suspension is a little soft for anything like spirited riding. if it still has all it's street gear, the first fixes are to figure out how much of that you can live without and meet your street needs. the plastic tank that came on our xr250r's is much lighter than the street version. so find one. the forks off the cr's from 86,87,88 and the 89 (cr 125 only in this case), go on pretty easy. it makes a big difference in the dirt.
set the valves before you ride it much, and then check them to see if they are growing clearance. I have a really modified 95 and right now I am putting a pretty close to stock one back together since the modded one is really not what I always want. it has a lot of things I wouldnt do again, but the suspension is well worth it, and if you look on ebay you can find what you need to do it reasonably. at the very least you will want to stiffen the existing forks on yours. i am not sure if the L version came with the 41mm cartridge forks that the R version did. it it did you can sell those with the front wheel to people who want to improve an xr200 or crf230 for as much as you will spend upgrading yours to 43 mm forks.
in the meantime you have a really reliable go anywhere kind of bike. just start by the valve settings.
there are lots of big bore kits available for that one, but only consider it if you need a rebore anyway.