I had it easy with DS. He ate pretty much anything from the start and with the exception of obvious cheese (ie not melted in/on something) ,raw tomatoes and curry, he still will now at 4.5
20 month old DD is a whole different matter and I have no idea what to do.
She eats breakfast well, in fact the first thing she does when we get downstairs in the mornings is to stand at her high chair and call to be lifted in. She will then happily devour between 1 and 2 weetabix normally so she is obviously hungry. From then on it gets harder.
She won't eat sandwiches or soup or quiche or any of the usual lunchtime things, she turns her nose up at salad and dip. If I give her something she does like - today we had noodles and spring rolls - she'll eat a very little bit then stop. Same with dinner. She will eat pasta with a tomato-y/bolognese sauce, beans or pretty much anything 'Little Dish' make but apart from that, she just pashes it away and refuses 
She used to love baked potatoes with cheese and beans but even that got pushed away yesterday, her previous favourite of quesadillas got refused last week too - she's getting worse and I'm panicing.
She must be hungry because when I call "dinner" or "lunch" she comes running and stands next to her highchair ready to be lifted in but then she'll take one look and turn her nose up. She must be hungry as she's only eating breakfast everyday!
Today I made plain, pan-fried haddock, boiled new potatoes, brocolli, asparagus and some purple cauliflower - all reasonably bland and easy to eat. I even gave her a blob of ketchup to help it go down but bar dipping her fork in the ketchup a few times she ate nothing. Then comes to argument between me and DH - I think she's too little to understand that she must eat her dinner to get a yogurt for dessert (although we do say this to her - repeatedly) and he thinks she's just waiting for the yogurt and shouldn't get anything if she won't eat her meal. The latter is how we work it for DS but he's almost 3 years older and so has more understanding of consequences. He thinks the yogurt fills her up just enough so that's all she wants. We refused her the yogurt today and let her down from the table but then she just cried as DS got his yogurt because he'd eaten everything on his plate and she wanted one too. I have tried giving other 'desserts' but she won't eat fruit either. She's eaten it in the past but very, very rarely, that usually gets pushed away too. On the odd occasion she does eat, there are lots of smiles and "Good girl"'s. If she's not eating, I usually leave her to it while I eat my food and then try to spoon feed her myself when I'm done - although this never works.
DD is also a very early riser (5.30am-6am) and I worry that not only is she too small to go without anything but that by not even giving her a yogurt, we risk her getting up even earlier because she is hungry. Beditme is about 7.30-8pm for both children.
All this is compounded for me by the fact that DD has always been tiny. She stuck to the 0.2 centile line in her book all the way up to a year. She's still wears 9-12 month clothes (she's just beginning to fit a few 12-18 month bits) despite being a few days off 20 months old. I'm just worried that she hasn't got a lot of weight to loose. I'm also worried that she's not getting enough nutrients in her diet of weetabix and mid morning smoothies. She's still dirtying at least 1 nappy a day so something is getting through, I'm just not sure what.
I have no idea where I've gone wrong or what to do next. Please help Mumsnet.
Sorry for the long post, I just wanted to get as much as I could think of down at the beginning.