The AAP recommends starting solid food from 4-6 months. I always recommend starting it at 4 months. Besides it being fun and cute, I feel babies usually are ready by 4 months and I truly feel the longer it takes to try solids, the greater the chance that child can have some food aversions since they've only been used to liquids their short life. It's important to get used to different textures younger. And not from a baby led weaning program which I don't agree with. I feel my own version of a baby led weaning program is a more safer version of it.
You want to do solids twice a day. My two main rules are....the 72 hour rule where only one new food is introduced in a 72 hour time span. As well as the rule of always doing the new food in the AM, so if there is a reaction, then you know where is it coming from.
I recommend starting with cereal first. Try oatmeal and rice cereal. Even if fearful of rice causing constipation, try it for three days because rice and oatmeal are the two most common cereals mixed in with other foods in a jar, so try it now to make sure there is no reaction. Mix one tablespoon of the cereal flakes with formula or breastmilk to find that right texture your infant will like. It might be thicker or it might be thinner. Usually you have to mix 1/4-1 oz of liquids to the desired consistency.
Then after we tolerate cereals, we can move onto some fruits and some veggies. I recommend orange veggies (sweet potatoes, carrots and squash) and some fruits (apples, bananas, pears, peaches, prunes, apricots, plums, grapes). You can alternate every 3 days with a fruit, then veggies, or vice versa. It will be with the cereal, so a cereal plus a fruit or cereal plus a veggie two times a day. Do 1/2 stage 1 jar or 1oz (1 ice cube) if you make it yourself at home. Work up to whole stage 1 jar or 2oz (2 ice cubes) by the end of the 4th month.
Bananas and apples can be constipating. Any food with the letter P can help you poop. Easy way to remember P for the fruit and P for poop. So, pears and prunes can work wonders there. Mix and match and have fun with it. You should do the new food in the AM, but can always go back to an older food already tolerated in the PM feeding. You don't have to be bored doing the same food 2x per day for 3 days.
Most importantly, get out the video camera. I'm sure the baby will be wearing half and you the other half! Enjoy!