Hi,
Starting well :).
But best to keep all riders 'all disciplines'. They level up slower which means they stay with you longer and build up good show experience.
You can have any single discipline horse with that same rider.
Keep to the lower levels early on, as the horses and riders develope they will naturally go up. The level 9 riders are expensive. So not worth having until several of your own horses go up to level 9.
So if buying in, get a few more level 3 + 4 horses. Pick horses by eventing level + 'sort by winnings' down at bottom of search tool. Do not look at sex, they all win. Mares are as good as geldings after the initial few weeks.
I find PEE & EEE horses give me great profits. Yes W might be better but you have to pay so much more, so longer to actually get profit. You want to get back the purchase price in first month of owning the the horse. All level horses will make a profit. But it is slower as you go down the ratings.
Keep in mind that the best profit is made if your rider has 5 or more horses. Then the winnings pay for the rider + some profit.
Don't do futurity yet when breeding as the winners are mostly all W horses. Leave that to later when your herd improves, at the moment it would be a money sink.
Best of luck.
Bright Sunshine with a few High Clouds
