yeah you could start your track that way, make sure you have at least a couple of off camber and camber turns to keep the variety, use the fallen trees to your advantage depending on size you can make an obstacle out of them, also dependant on the gradient of the slope and its length will also determine the number of straights and bends and obstacle's in the track you don't want a constant barrage of obstacle's because there will be no flow.

I believe there have been a few other topics about this recently with some good ideas and how to start, just use the search button for any more ideas mate

hope that helps

Adam

you want to keep the top of the track with a couple of pump sections then most likely, build up a bit of speed and go slightly across the slop at about a 30 degree angle, then burm into the steeper section were you want a couple of obstacles to keep a nice flow of speed with burms at points so that there isn't any over braking on that section so not to form any brake bumps.

You could use those trees as part of those obstacles there then. When you get to the flatter section you could add a couple of the jumps there and connect it with some tight, fast burms to keep the flow and feel of a DH track without it just turning into a rhythm.

The hardest part is to decide were exactly to put obstacles so it flows well, you should mark out a general line ride it at an average pass and try and visualise were the obstacles can fit nicely between the track so that it has a nice constant flow, take one obstacle at a time and work down the hill.

If you don't like one type of obstacle were it is then you don't have to do too much but you may decide you want something similar before or after were speed may need to be scrubbed in that section.

Rock gardens and rooty sections are good for that along with burms around trees so that its tighter, try adding some small drops as you go down the sections too. They don't have to be large to be fun and you don't want to over size anything that will either ruin the flow or make the track that much shorter because you focused on one object and you need a long run in and/or exit.

Make drops which lead directly into another small object or a slight of camber turn to a close by tree. 

If it is mostly grass (like a field) dont bother trying to cut up the grass it will be pretty pointless in my opinion. You might as well dig into it or onto it. You said its in woodland so i doubt its like that.
If so your best bet is to rake off the top layer of rubbish on the floor which will also mark out your track. If its a pretty short track the best way to lengthen it is obviously to cut across and not go straight down. However you don't want this to slow you down but to maintain your speed through the corners and any other obstacles. Make sure you have a good look for anything which could add some natural features, such as round trees, some semi exposed roots could be used and possibly exposed slightly more to make a feature, possibly an interesting off camber.
It depends if the fallen trees are in the right place, if when your marking out your track then it looks in the way and not worth a jump then get out the saw and move it. But they can be useful, make sure its stable and stake the back of it if you need to.

With a rock garden it will be nice to find a natural rock pile, you can sometimes find them after scraping off the top layer bracken etc, ive sen some laughable attempts at rock gardens before so unless you have a nice supply of rocks then i wouldn't concentrate to much on it.

cheers for all the sound advice.

Ive just been up and taken a few piccys(well alot lol) so il post them up and you can tell me what you tyhink.

here ya guys goe

sorry bout the size and amount lol

yep top down

pics 3-9 are right at the top if you turn left from the first picture

With some of those fallen trees you could build a north shore/ boardwalk onto them. It doesn't have to be very high, but it will be more interesting and would look sweet.

Ben